Compositions comprising silk fibroin particles and uses thereof

ABSTRACT

Various aspects described herein relate to compositions comprising silk fibroin particles and methods of using the same, as well as devices and methods of delivering such compositions. The compositions described herein are suitable for injection into a site of defect in a soft tissue to provide bulking and/or augmentation effect to the soft tissue.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/799,455, filed Oct. 31, 2017, which claims the benefit under 35U.S.C. § 119(e) of U.S. provisional application No. 62/415,107 filedOct. 31, 2016; U.S. provisional application No. 62/482,949 filed Apr. 7,2017; U.S. provisional application No. 62/488,402 filed Apr. 21, 2017;and U.S. provisional application No. 62/571,670 filed Oct. 12, 2017, thecontents of each of which are incorporated herein by reference in theirentirety.

TECHNICAL FIELD

Various aspects described herein relate to compositions comprising silkfibroin particles for biomedical applications, e.g., in soft tissueaugmentation, repair, and/or tissue regeneration.

BACKGROUND

Biomaterials or synthetic ceramic or polymeric materials have been usedas bulking agents for soft tissue augmentation. For example, syntheticceramic materials such as calcium hydroxylapatite (CaHA) suspended incarboxymethylcellulose have been used as laryngeal implants forcorrection of vocal fold paralysis or other causes of vocal foldinsufficiency. Biomaterials such as collagen or hyaluronic acid havebeen used as injectable dermal fillers to provide temporary augmentationin a facial tissue or other soft tissue. While these biomaterialsprovide immediate bulking to the desired area, they degrade fast andthus require repeated treatment every few months. Synthetic polymericmaterials (e.g., poly(lactic acid), poly(glycolic acid), and poly(methylmethacrylate)), silicone implants, and saline implants can provide alonger bulking effect, but they are less compatible with soft tissue andtheir use may cause certain complications including inflammation orscaring. Additionally, injection of these materials may provide atemporary protection from radiation damage by reducing collateralexposure. For example, an injection through the perineum into theanatomical space between the prostate gland and the rectum can providetemporary protection for men with prostate cancer who are undergoingradiotherapy from collateral damage to neighboring tissue, specificallyto the rectal tissues.

Accordingly, there is a need to develop novel compositions that areinjectable and are more effective for soft tissue augmentation, repair,and/or tissue regeneration. There is also a need for delivery devices todeliver such compositions.

SUMMARY

Embodiments of some aspects described herein are based on, at least inpart, discovery of low extrusion force, injectable compositions (e.g.,comprising highly-crosslinked hyaluronic acid), which, when administeredalone, generally requires high extrusion force for administration byinjection. These materials may provide immediate soft tissue bulking,while also acting to promote soft tissue regeneration over time. Thus,these new materials may be used to provide longer-lasting augmentationand/or correct aging or sagging of soft tissue by targeting andpromoting tissue regeneration.

For example, while highly-crosslinked hyaluronic acid lasts longer invivo than that of a low-crosslinked hyaluronic acid, thehighly-crosslinked hyaluronic acid, when administered alone, typicallyexhibits a non-uniform extrusion profile in which the average extrusionforce fluctuates during injection, which makes it an undesirable carrieras an injectable material. As described herein, it was discovered thatwhen highly-crosslinked hyaluronic acid is mixed with biocompatibleparticles, e.g., silk fibroin particles, such a composition not only ismore resistant to degradation in vivo than the highly-crosslinkedhyaluronic acid alone, but also exhibits shear thinning behavior and canbe extruded through a needle more smoothly than highly-crosslinkedhyaluronic acid using a lower extrusion force. The hyaluronic acidcomponent may promote immediate soft tissue augmentation, while thebiocompatible particles, e.g., silk fibroin particles, may act toregenerate soft tissues, e.g., collagen, and provide a longer-lastingaugmentation to the injected area.

Other aspects described herein relate to discovery of compositionscomprising silk fibroin particles that (i) are compatible (e.g.,biologically and/or mechanically) with soft tissue; (ii) are tunable toprovide soft tissue augmentation for appropriate duration (e.g., toprovide a long-lasting bulking effect to a soft tissue in need thereof);(iii) are consistently manufactured to a uniform composition and poresize; and (iv) are injectable. The inventors have also discoveredcompositions comprising silk fibroin particles and hyaluronic acid(e.g., highly crosslinked hyaluronic acid) that are suitable for use invocal cord medialization or as soft tissue filler materials, e.g. asdermal fillers, as these compositions are biocompatible and extendtreatment length (thus reducing the need for frequent re-injection).

The compositions of various aspects described herein can be used for anysuitable biomedical applications such as soft tissue augmentation,tissue regeneration and/or ingrowth, cellular scaffolding, and/or woundsealing or clotting. In some embodiments, the compositions describedherein can be also configured for drug delivery, e.g., incorporating anactive agent into the compositions or silk fibroin particles or carrieras described herein. In some embodiments, the compositions are used as adermal filler. In some embodiments, the compositions are used as aninjectable implant for vocal fold augmentation. Other applications arealso possible.

One aspect provided herein relates to an injectable compositioncomprising crosslinked hyaluronic acid carrier and biocompatibleparticles, wherein the crosslinked hyaluronic acid has a crosslinkdensity of about 4 mol % to about 30 mol %, and wherein the compositionis characterized in that a standard deviation of extrusion force of thecomposition through a 18-30 (e.g., 18, 19, 20, 21, 22, 23, 24, 25, 26,27, 28, 29, or 30) gauge needle into air, as determined between about50% extrusion volume and about 90% extrusion volume, is less than about40% of an average extrusion force for the corresponding range of theextrusion volume.

Another aspect described herein relates to an injectable compositioncomprising crosslinked hyaluronic acid carrier and biocompatibleparticles, wherein the crosslinked hyaluronic acid has a crosslinkdensity of about 4 mol % to about 30 mol %, and wherein the compositionis characterized in that a stiffness of the composition under externalstrain is decreased by at least about 10% as measured between about 10%strain and about 90% strain. In some embodiments, the stiffness of thecomposition may be decreased by at least about 20%, at least about 30%,at least about 40%, or at least about 50% or more, as measured betweenabout 10% strain and about 90% strain. In some embodiments, thestiffness of the composition is measured when the composition is fullysaturated with water.

In some embodiments involving the compositions described above andherein, the biocompatible particles and the crosslinked hyaluronic acidare present in a volume ratio of about 5:95 to about 95:5.

The particles present in the compositions described above and herein mayhave an average particle size of about 50 μm to about 1000 μm. In someembodiments, the particles may have an average particle of about 60 μmto about 140 μm. In some embodiments, the particles may have an averageparticle of about 75 μm to about 125 μm. In some embodiments, theparticles may have an average particle of about 325 μm to about 450 μm.In some embodiments, the particles may have an average particle of about355 μm to about 425 μm. In some embodiments, smaller particles or largerparticles may be used provided that the average force extruding about 1mL of the composition through a 18-30 gauge needle into air remains lessthan 60N (including, e.g., less than 50 N, less than 40 N, or less than30 N).

In some embodiments involving the compositions described above andherein, where the crosslinked hyaluronic acid and the particles arepresent in a volume ratio of between about 80% (v/v) particles to about20% (v/v) HA and about 20% (v/v) particles to about 80% (v/v) HA, theaverage particle size is between about 200 μm to about 600 μm, and anaverage force of extruding about 1 mL of the composition through a 18-21gauge (e.g., 18, 19, 20, 21) needle into air is about 40 N or lower.Alternatively, an average force of extruding about 1 mL of thecomposition through a needle with a larger gauge size (e.g., 22, 23, 24,25, 26, 27, 28, 29, 30) is less than about 50 N. In some embodiments,the crosslinked hyaluronic acid and the particles are present in avolume ratio of between about 70:30 to about 30:70, the average particlesize is less than about 200 μm, and an average force of extruding about1 mL of the composition through a 21-30 (e.g., 21, 22, 23, 24, 25, 26,27, 28, 29, or 30) gauge needle into air is about 40 N or lower. In someembodiments, the crosslinked hyaluronic acid and the particles arepresent in a volume ratio of about 60% (v/v) particles to about 40%(v/v) HA, the average particle size is between about 325 μm to about 450μm, and an average force of extruding about 1 mL of the compositionthrough a 21-30 (e.g., 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30) gaugeneedle into air is about 40 N or lower.

The particles may comprise any biocompatible material that is suitablefor soft tissue augmentation and/or drug delivery in vivo. For example,in some embodiments, the particles may comprise a polymer, a silkfibroin, a protein, a peptide, or combinations thereof. In someembodiments, the particles are silk fibroin particles.

The particles present in the composition described above and herein maybe porous or non-porous. In some embodiments, the particles are porous.In these embodiments, the porous particles may have a porous structurecharacterized by interconnected pores having an average pore size ofabout 1 μm to about 100 μm, or about 20 μm to about 100 μm, or about 1μm to about 10 μm. In some embodiments, the particles may have poresthat are too small to be measured. In some embodiments, the porousparticles may have an average porosity of at least about 90% or higher.The porosity of the particles can be carefully controlled duringsynthesis and/preparation of the material.

In some embodiments involving the compositions described above andherein, the crosslinked hyaluronic acid can have a concentration ofabout 1% (w/v) to about 10% (w/v).

The compositions described herein can exist in different states, e.g.,in hydrated state or dried state.

Another aspect described herein relates to a novel porous silk fibroinparticle that exhibits little or minimal plastic deformation and itspores exhibit substantially rounded morphology. For example, the silkfibroin particle has an average particle size of about 50 μm to about1000 μm and a porous structure characterized in that:

no more than about 10% of pores within the porous structure have anaspect ratio of about 4.0 or higher; and

when a population of the silk fibroin particles is exposed to acompressive strain of at least about 20%, the silk fibroin particlesrecover at least about 90% of their original volume after release of thecompression.

In some embodiments involving the silk fibroin particle described aboveand herein, the population of the silk fibroin particles may have anelastic modulus of at least about 5 kPa or higher (as measured at a6-10% axial strain).

In some embodiments involving the silk fibroin particle described aboveand herein, at least about 40% (including, e.g., at least about 50%, atleast about 60%, at least about 70%, or more) of the pores have anaspect ratio of about 1.0 to about 2.0.

In some embodiments involving the silk fibroin particle described aboveand herein, the pores of the silk fibroin particle have an averageaspect ratio of about 1.5 to about 2.5.

In some embodiments involving the silk fibroin particle described aboveand herein, the pores of the silk fibroin particle have an averagecircularity of about 0.4 to about 1.0, or about 0.5 to about 0.9, orabout 0.6 to about 0.8.

In some embodiments involving the silk fibroin particle described aboveand herein, the silk fibroin particle can comprise a plasticizer.Examples of a plasticizer include, but are not limited to an alcohol, asugar, a polyol, or any combinations thereof. In one embodiment, theplasticizer is glycerol.

In some embodiments involving the silk fibroin particle described aboveand herein, the porous structure of the silk fibroin particle ischaracterized by interconnected pores having an average pore size ofabout 1 μm to about 100 μm. In some embodiments, the silk fibroinparticle can have an average porosity of at least about 90% or higher.

The silk fibroin particles described herein can exist in differentstates, e.g., in hydrated state or dried state. In some embodimentsinvolving the silk fibroin particle described above and herein, the silkfibroin particles are lyophilized silk fibroin particles.

In some embodiments involving the silk fibroin particle described aboveand herein, the silk fibroin particle may comprise residual chemical(s).For example, in some embodiments, the silk fibroin particles (having anaverage particle size of about 300 microns to 450 microns) can possessno more than 250 micrograms of residual lithium in an about 1 mL dosecontaining about 40% v/v silk fibroin particles. In some embodiments,the silk fibroin particles (having an average particle size of about 300microns to 450 microns) can possess no more than 250 micrograms ofresidual bromide in about 1 mL dose containing about 40% v/v silkfibroin particles. In some embodiments, the silk fibroin particles(having an average particle size of about 300 microns to 450 microns)can possess no more than 30 mg of residual methanol in an about 1 mLdose containing about 40% v/v silk fibroin particles.

In some embodiments involving the porous silk fibroin particle describedabove and herein, the porous silk fibroin particle may have an averagedensity (when the particles in dried form, e.g., dried andnon-compressed silk fibroin particles) of about 0.05 g/mL particles toabout 0.2 g/mL particles, or about 0.08 g/mL particles to about 0.15g/mL particles, or about 0.1 g/mL particles to about 0.13 g/mLparticles.

In some embodiments involving the silk fibroin particle described aboveand herein, the silk fibroin particle may be hydrated, e.g., in anaqueous solution, including, e.g., but not limited to water, saline,and/or a buffered solution such as a phosphate buffered solution. Inthese embodiments, the hydrated silk fibroin particle may have anaverage density (when the particles are in hydrated form, e.g., hydratedand non-compressed silk fibroin particles) of about 0.4 g/mL particlesto about 1.0 g/mL particles, or about 0.6 g/mL particles to about 0.8g/mL particles.

In some embodiments involving the porous silk fibroin particle describedabove and herein, the porous structure may be characterized byinterconnected pores having an average circle equivalent diameter ofabout 25 μm to about 55 μm, or about 30 μm to about 50 μm.

In some embodiments involving the porous silk fibroin particle describedabove and herein, the porous structure may be characterized by no morethan 10% (including, e.g., no more than about 9%, no more than about 8%,no more than about 7%, no more than about 6%, no more than about 5% orlower) of interconnected pores having a circle equivalent diameter ofabout 100 μm or greater.

In some embodiments involving the porous silk fibroin particle describedabove and herein, the porous structure may be characterized byinterconnected pores having an average circle equivalent diameter ofabout 25 μm to about 55 μm, or about 30 μm to about 50 μm.

In some embodiments involving the porous silk fibroin particle describedabove and herein, the porous structure may be characterized by no morethan 10% (including, e.g., no more than about 9%, no more than about 8%,no more than about 7%, no more than about 6%, no more than about 5% orlower) of interconnected pores having a circle equivalent diameter ofabout 100 μm or greater.

In some embodiments involving the porous silk fibroin particle describedabove and herein, the porous structure may be characterized by at leastabout 60% (including, e.g., at least about 70%, at least about 80%, atleast about 90% or more) of interconnected pores having a circleequivalent diameter of about 75 μm or lower.

In some embodiments involving the porous silk fibroin particle describedabove and herein, the porous structure may be characterized by at leastabout 80% (including, e.g., at least about 85%, at least about 90%, atleast about 95% or more and up to 100%) of interconnected pores having acircle equivalent diameter of about 15 μm to about 100 μm.

Also provided herein are compositions comprising one or more silkfibroin particles as described above and herein and a carrier. In someembodiments, the silk fibroin particles and the carrier are in a volumeratio of about 5:95 to about 95:5. In some embodiments, the silk fibroinparticles are substantially monodispersed.

The carrier can comprise a single carrier or a mixture of two or morecarriers (e.g., a first carrier and a second carrier of the samedifferent weight average molecular weights). Non-limiting examples ofthe carrier include glycosaminoglycan polymers (e.g., hyaluronic acid,crosslinked hyaluronic acid, keratan sulfate, chondroitin sulfate,and/or heparin), extracellular matrix protein polymers (e.g., collagen,elastin, and/or fibronectin), polysaccharides (e.g., cellulose), fibrousprotein polymers, a fat material (e.g., derived from a lipoaspirate),and a combination of two or more thereof.

In some embodiments involving the compositions described above andherein, the carrier comprises non-crosslinked or crosslinked hyaluronicacid polymer. In some embodiments, the hyaluronic acid polymer may havea weight average molecular weight of about 200 kDa to about 5 MDa. Insome embodiments where there are at least two carriers, the firstcarrier may comprise hyaluronic acid with a weight average molecularweight of about 200 kDa to about 1 MDa, and optionally wherein thesecond carrier comprises hyaluronic acid with a weight average molecularweight of about 200 kDa to about 5 MDa. In some embodiments, thehyaluronic acid polymer may have a concentration of about 0.1% w/v to10% w/v.

In some embodiments involving the compositions described above andherein, where the carrier comprises crosslinked hyaluronic acid, thecomposition may comprise residual chemical(s). For example, in someembodiments, about 1 mL dose of the composition comprising 40% v/v silkfibroin particles (having an average particle size of about 300 micronsto 450 microns) and 60% v/v hyaluronic acid can possess no more than 250micrograms of residual lithium. In some embodiments, about 1 mL dose ofthe composition comprising silk fibroin particles (having an averageparticle size of about 300 microns to 450 microns) can possess no morethan 250 micrograms of residual bromide. In some embodiments, about 1 mLdose of the composition comprising 40% v/v silk fibroin particles(having an average particle size of about 300 microns to 450 microns)and 60% v/v hyaluronic acid can possess no more than 30 mg of residualmethanol. In some embodiments, the crosslinked hyaluronic acid in thecomposition can comprise no more than 2 ppm residual crosslinking agent(e.g., 1,4-butanediol diglycidyl ether (BDDE)).

The average particle size of the silk fibroin particles in someembodiments involving the compositions described herein may be selectedto suit the need of each application. For example, smaller averageparticle size may be desirable for treatment of fine lines and wrinkles,while larger average particle size may be more suitable for vocal foldaugmentation or even large volume reconstruction (e.g., breastreconstruction). Accordingly, in some embodiments, the silk fibroinparticles have an average particle size of about 250 μm to about 450 μm,or about 300 μm to about 400 μm. In alternative embodiments, the silkfibroin particles may have an average particle size of about 400 μm toabout 600 μm or about 450 μm to about 550 μm. In some embodiments, thesilk fibroin particles may have an average particle size of about 50 μmto about 200 μm. In some embodiments, the silk fibroin may have anaverage particle size of about 75 μm to about 125 μm. In someembodiments involving the compositions described above and herein, aplurality of the particles (e.g., silk fibroin particles in a carriermatrix) may be delivered through a tube having an inside diameter thatallows particles to be delivered at a low extrusion force. In someembodiments, the tube may have an inside diameter of at least about 0.5mm, at least about 0.7 mm, at least about 0.8 mm, at least about 0.85mm, at least about 0.9 mm, at least about 0.95 mm, at least about 1 mm,at least about 1.05 mm, at least about 1.1 mm, at least about 1.15 mm,or at least about 1.2 mm. In some embodiments, the tube may have aninside diameter of less than or equal to about 1.5 mm, less than orequal to about 1.3 mm, less than or equal to about 1.2 mm, less than orequal to about 1.15 mm, less than or equal to about 1.1 mm, less than orequal to about 1.05 mm, less than or equal to about 1 mm, less than orequal to about 0.95 mm, less than or equal to about 0.9 mm, or less thanor equal to about 0.8 mm. Combinations of the above-referenced rangesare also possible. For example, in some embodiments, the tube may havean inside diameter of about 0.5 mm to about 1.5 mm, or about 0.7 mm toabout 1.3 mm, or about 0.9 mm to about 1.1 mm.

The composition may be characterized in that a standard deviation ofextrusion force of the composition through a 18-30 gauge needle intoair, as determined between about 50% extrusion volume and about 90%extrusion volume, is less than about 40%, less than about 30%, less thanabout 20%, or less than about 10%, of an average extrusion force for thecorresponding range of the extrusion volume. The needle may be designedto further reduce the extrusion force of the composition.

In some embodiments involving the compositions described above andherein, the composition is characterized in that stiffness of thecomposition is decreased by at least about 10%, at least about 20%, atleast about 30%, at least about 40%, or at least about 50% as measuredbetween about 10% strain and about 90% strain.

In some embodiments involving the compositions described above andherein, the composition is characterized in that an average force ofextruding about 1 mL of the composition through an 18-30 gauge needleinto air is about 5 N to about 40 N.

In some embodiments involving the compositions of any aspects describedabove and herein, the injectable composition may be pre-loaded in asyringe. In some embodiments, the syringe is coupled to a tube via ahandle so that the composition may be injected through the tube. Thistube may further be coupled to an endoscope or laryngoscope during aprocedure. The needle may be a hollow needle that is attached to thetube. The tube may be positioned within and moveable within an outersheath tube. The needle may be moveable between a retracted positionwithin the outer sheath tube and an extended position in which theneedle tip is outside the outer sheath tube to control injection of thecompositions. In some embodiments, the outer sheath tube, with theneedle and inner tube inside the outer sheath tube, is inserted into thechannel of an endoscope. The delivery device may include a handle thatcan be actuated by a user to move the inner tube distally relative tothe outer tube sheath, thereby advancing the needle distally through theouter sheath tube toward an extended position in which the needle tip isexposed for injection of the compositions into a tissue or region ofinterest.

In some embodiments involving the compositions of any aspects describedabove and herein, the compositions may include any suitable inactiveingredient included in U.S. Food & Drug Administration (FDA)'s databasefor Generally Recognized as Safe (GRAS) substances, which is accessibleonline at accessdata.fda.gov/scripts/fdcc/?set=SCOGS.

The compositions and injectable compositions described above and hereincan be implanted or injected to a subject in need thereof. For example,the compositions and injectable compositions described herein can beused for treating a target site in a soft tissue of a subject, e.g., forsoft tissue augmentation and/or ingrowth. Accordingly, methods foraugmenting or regenerating different soft tissues are provided herein.In some embodiments, such a method comprises injecting to a target site(e.g., a site of defect or a void) in a soft tissue a compositioncomprising silk fibroin particles of any embodiments or aspectsdescribed herein and a carrier, or a composition as described above orherein. The silk particles provide a bulking effect to the soft tissueby maintaining up to about 80% (including, e.g., up to about 50%, up toabout 60%, up to about 70% or up to about 80%) of the particles'original volume for at least about 3 months or longer after theinjection. In some embodiments, the composition can be injected throughan 18-30 needle using an average extrusion force of no more than 60 N,including, e.g., no more than 50 N, no more than 40 N, or lower.

The methods described herein and/or compositions described herein can beapplied to treat different soft tissues for small volume bulking orlarge volume bulking applications, including but not limited to, a skintissue, e.g., a facial skin tissue, a bladder tissue, a cervical tissue,a vocal fold tissue, a breast tissue, or a buttock tissue. For example,in some embodiments, particle size of the particles used in the methodsand/or compositions described herein can be tuned to meet requirementsof the volume bulking site. Additionally or alternatively, the injectionvolume of the compositions described herein can also be tuned to meetrequirements of the volume bulking site. For example, in someembodiments for large volume bulking applications (e.g., but not limitedto breast reconstruction, buttock reconstruction, and treatment oflipodystrophy), the composition can be injected in an amount of at leastabout 3 cm³ or more. In these embodiments, the composition can beinjected in an amount that is sufficient to fill and conform to theshape of a void at the target site. In these embodiments, the method mayoptionally further comprise allowing cells from tissue surrounding thetarget site to interact with the silk fibroin particles, wherein thesilk fibroin particles maintain at least about 30% of their volume forat least about 9 months or longer after the injection, therebyaugmenting or regenerating the soft tissue. In some embodiments, thesilk fibroin particles maintain at least about 30% of their volume forat least about 12 months or longer after the injection.

In some embodiments involving large volume bulking applications, thecomposition is injected through a 18-21 gauge needle using an averageextrusion force of no more than 60 N, including, e.g., no more than 50N, no more than 40 N, or lower.

In other embodiments for small volume bulking applications, thecomposition may be injected with a 21-30 gauge needle using an averageextrusion force of no more than about 30 N. Examples of small volumebulking applications include, but are not limited to a dermal filler forskin tissue (e.g., treatment of facial skin tissue having a facial line,or wrinkle, or a scar to be filled), bulking of urethra (e.g., treatmentfor stress-urinary incontinence), bulking of cervical tissue (e.g.,treatment for cervical insufficiency), and bulking of vocal fold (e.g.,correction of vocal fold paralysis or other causes of vocal foldinsufficiency). In these embodiments, the composition can be injected inan amount of about 3 cm³ or less.

In some aspects, methods of augmenting a vocal fold in a subject in needthereof are also provided herein. For example, in one aspect, the methodcomprises injecting to a target site (e.g., a glottal gap) in the vocalfold of the subject a composition comprising a crosslinked matrixcarrier and porous silk fibroin particles, wherein the composition ischaracterized in that:

-   -   (i) the crosslinked matrix carrier has a crosslink density of        about 4 mol % to about 30 mol %;    -   (ii) the porous silk fibroin particles and the crosslinked        matrix carrier are present in a volume ratio of about 80% (v/v)        silk fibroin particles: about 20% (v/v) HA, to about 20% (v/v)        silk fibroin particles: about 80% (v/v) HA; and    -   (iii) a standard deviation of extrusion force of the composition        through a 18-21 gauge needle into air, as determined between        about 50% extrusion volume and about 90% extrusion volume, is        less than about 40% (including, e.g., less than about 30%, less        than about 20% or lower) of an average extrusion force for the        corresponding range of the extrusion volume.

In some embodiments, the porous silk fibroin particles and thecrosslinked matrix carrier are present in a volume ratio of about 60%(v/v) silk fibroin particles: about 40% (v/v) HA.

In another aspect, the method comprises injecting to a target site(e.g., a glottal gap) in the vocal fold of the subject a compositioncomprising a crosslinked matrix carrier and porous silk fibroinparticles, wherein the composition is characterized in that:

-   -   (i) the crosslinked matrix carrier has a crosslink density of        about 4 mol % to about 30 mol %;    -   (ii) the porous silk fibroin particles and the crosslinked        matrix carrier are present in a volume ratio of about 60:40 to        about 20:80; and    -   (iii) a stiffness of the composition is decreased by at least        about 10% (including, e.g., at least about 20%, at least about        30%, at least about 40%, at least about 50%, at least about 60%,        or more) as measured between about 10% strain and about 90%        strain.

In some embodiments, the stiffness of the composition is measured whenthe composition is in a fully water saturated state.

In any aspects described herein involving methods for augmenting vocalfolds, the porous silk fibroin particles provide bulking effect to thevocal fold by maintaining up to about 80% (including, e.g., up to about50%, up to about 60%, up to about 70% or up to about 80%) of theparticles' original volume for at least about 3 months or longer afterthe injection.

In some embodiments involving vocal fold augmentation, the crosslinkedmatrix carrier comprises crosslinked glycosaminoglycan polymers (e.g.,crosslinked hyaluronic acid), crosslinked extracellular matrix proteinpolymers (e.g., crosslinked collagen, crosslinked elastin, and/orcrosslinked fibronectin), crosslinked polysaccharides (e.g., crosslinkedcellulose), crosslinked fibrous protein polymers, and a combination oftwo or more thereof. In some embodiments, the crosslinked matrix carrier(e.g., crosslinked hyaluronic acid) has a concentration of about 0.1%w/v to 10% w/v.

Any porous silk fibroin particles described herein can be used for themethods described herein for vocal fold augmentation. In someembodiments, the porous silk fibroin particles can comprise aplasticizer, examples of which include, but are not limited to analcohol, a sugar, and/or a polyol (e.g., glycerol). In some embodiments,the porous silk fibroin particles have an average particle size of about50 μm to about 500 μm, or about 300 μm to 450 μm. In some embodiments,the porous silk fibroin particles have a porous structure characterizedby interconnected pores having an average pore size of about 20 μm toabout 100 μm. In some embodiments, the porous silk fibroin particleshave an average porosity of at least 90%. In some embodiments, theporous silk fibroin particles and the crosslinked matrix carrier arepresent in a volume ratio of about 30:70 to about 70:30 or about 30:70to about 50:50.

In some embodiments involving the compositions and/or methods describedabove and herein, the subject in need thereof has vocal cord paresis,paralysis, or glottic insufficiency. In some embodiments, the injectioncan comprise trans-oral injection, trans-nasal injection, percutaneousinjection, or thyroid injection. In some embodiments, the injection istrans-oral or trans-nasal injection, which, for example, may beperformed with a device for delivering the composition to the site ofdefect in the vocal fold.

According to one aspect, a method of administering a composition to asubject is provided. The method can comprise, in some embodiments,inserting a needle and a catheter of a delivery device into the subject,the needle being coupled to and in fluid communication with thecatheter. The method may also include moving the needle toward aninjection site of the subject. The method may also include actuating ahandle of the delivery device to move the needle from a retractedposition to an extended position, where actuating the handle comprisessliding a first portion of the handle relative to a second portion ofthe handle from a first discrete position to a second discrete position.The method may also include inserting the needle into the injection siteand delivering a composition comprising silk fibroin particles throughthe catheter and the needle into the injection site.

According to another aspect, a method of administering a composition toa subject is provided. The method can comprise, in some embodiments,inserting a needle and a catheter trans-orally or trans-nasally into thesubject, the needle being coupled to and in fluid communication with thecatheter. The method may also include moving the needle toward a vocalfold of the subject, inserting the needle into the vocal fold anddelivering a composition comprising particles through the catheter andthe needle into the vocal fold.

According to yet another aspect, a device for delivering a compositionto a subject is provided. The device can comprise, in some embodiments,a hollow needle, an outer sheath tube and an inner tube. The inner tubeand the needle may be movable within the outer sheath tube, a proximalend of the inner tube being configured to couple to a container forholding composition. A distal end of the inner tube may be coupled toand in fluid communication with the needle. The device may also includea handle coupled to the outer sheath tube. The handle may be configuredto couple the outer sheath tube to the container. A length of the innertube from the proximal end to the distal end may be 20 cm to 60 cm.

Other advantages and novel features of the present invention will becomeapparent from the following detailed description of various non-limitingembodiments of the invention when considered in conjunction with theaccompanying figures. In cases where the present specification and adocument incorporated by reference include conflicting and/orinconsistent disclosure, the present specification shall control. If twoor more documents incorporated by reference include conflicting and/orinconsistent disclosure with respect to each other, then the documenthaving the later effective date shall control.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting embodiments of the present invention will be described byway of example with reference to the accompanying figures, which areschematic and are not intended to be drawn to scale. For purposes ofclarity, not every component is labeled in every figure, nor is everycomponent of each embodiment of the invention shown where illustrationis not necessary to allow those of ordinary skill in the art tounderstand the invention.

FIG. 1 is a schematic representation of an exemplary method for makingsilk fibroin particles according to one set of embodiments describedherein.

FIG. 2 is a microscopic image of individual silk fibroin particlesaccording to one set of embodiments described herein. The porous silkfibroin particle have an average particle size of about 500 microns toabout 600 microns in diameter and an average pore size of about 40 μm indiameter.

FIGS. 3A-3B are two sets of photographs depicting responses of anexemplary silk fibroin bulk foam or sponge (FIG. 3B), from which silkfibroin particles of one set of embodiments described herein areproduced, to a compressive strain and after release of the compressivestrain, as compared to those of a silk hydrogel (FIG. 3A). FIG. 3A showsthat hydrogels are generally more suitable for spreading because theyare easily deformed, e.g., due to the nanoparticle sliding effect. FIG.3B shows that the silk fibroin foam or sponge are generally moresuitable for elasticity, control, and maintenance of a fixed particlesize. In one set of the embodiments described herein, the silk fibroinparticles are produced from a silk fibroin bulk foam or sponge describedin the International Patent Publication No. WO 2016/145281 entitled“Shape Memory Silk Materials,” which claims the benefit of U.S.Provisional Application No. 62/132,429 filed Mar. 12, 2015, the contentsof each of which is incorporated herein.

FIGS. 4A-4C are scanning electron microscopic (SEM) images offreeze-dried silk fibroin materials without glycerol. FIG. 4A shows theentire cross-section of the silk fibroin bulk material. FIG. 4B shows azoomed-in cross section of the silk fibroin bulk material. FIG. 4Cdepicts silk fibroin particles produced from the silk fibroin bulkmaterial of FIG. 4A or 4B.

FIGS. 5A-5C are scanning electron microscopic (SEM) images offreeze-dried silk fibroin materials with glycerol. FIG. 5A shows theentire cross-section of the silk fibroin bulk material. FIG. 5B shows azoomed-in cross section of the silk fibroin bulk material. FIG. 5Cdepicts silk fibroin particles produced from the silk fibroin bulkmaterial of FIG. 5A or 5B. The silk fibroin bulk materials in FIGS.4A-4C and FIGS. 5A-5C were produced from a silk fibroin solution at aconcentration of about 10% w/v. The silk fibroin solution of FIGS. 5A-5Chas glycerol at a concentration of about 3.33% w/w. The silk fibroinsolution (with or without glycerol) was subjected to freeze-drying tofabricate a sponge-like material, which was then immersed in an alcohol(e.g., methanol) to induce β-sheet formation. As compared to the silkfibroin material of FIG. 5B (comprising glycerol), the silk fibroinmaterial of FIG. 4B (without glycerol) contained a combination of poroussilk fibroin materials and larger non-porous crystals, which could beattributed to irregularities in freezing. Without wishing to be bound bytheory, glycerol may delay or slow freezing such that silk fibroin isnot exposed to extreme temperatures in such a rapid timeframe.

FIG. 6 shows subcutaneous delivery of a composition comprising silkfibroin particles according to one set of embodiments described hereinand a carrier to an animal for soft tissue augmentation. (Top) a mousewas injected with control compositions and compositions according to oneset of embodiments described herein; (bottom left) a biopsy of thetissue site injected with a mixture of silk fibroin particles and fat;and (bottom right) a biopsy of the tissue site injected with control(fat alone). In this example, about 30-50% silk fibroin particles weresuspended in a carrier (e.g., fat).

FIGS. 7A-7D are graphs showing extrusion forces resulting frominjections of lipoaspirate alone or in combination with silk fibroinparticles according to one set of embodiments described herein. FIG. 7A:force of extruding lipoaspirate alone through a 16G needle. FIG. 7B:force of extruding a mixture of 30% silk fibroin particles andlipoaspirate through a 16G needle. FIG. 7C: average extrusion forces ofindicated compositions using a 1 mL syringe, 14G needle system. FIG. 7D:average extrusion forces of indicated compositions using a 1 mL syringe,16G needle system. The percentages associated with silk fibroinparticles in the figures correlate to the volume ratio of silk fibroinparticles and human lipoaspirate in the mixture. For example, 30% silkrefers to a volume ratio of the silk fibroin particles to lipoaspiratebeing 30:70. The silk fibroin particles were extruded through 14G or 16Gneedles without clogging, and the rate of compressing the plunger of thesyringe was 5.5 mm/s, which corresponds to extrusion of 1 mL of materialin 10 seconds.

FIGS. 8A-8D are graphs showing extrusion forces resulting frominjections of non-crosslinked hyaluronic acid (HA) alone or incombination with silk fibroin particles according to one set ofembodiments described herein. FIG. 8A: force of extruding HA alonethrough a 14G needle. FIG. 8B: force of extruding HA alone through a 16Gneedle. FIG. 8C: force of extruding a mixture of silk fibroin particlesand HA in a volume ratio of 50:50 through a 14G needle. Theconcentration of HA was about 4% w/v. FIG. 8D: force of extruding amixture of silk fibroin particles and HA in a volume ratio of 50:50through a 16G needle. The concentration of HA was about 4% w/v. Thepercentages associated with silk fibroin particles in the figurescorrelate to the volume ratio of silk fibroin particles andnon-crosslinked HA in the mixture. For example, 50% particles refers toa volume ratio of the silk fibroin particles to 4% non-crosslinked HAbeing 50:50. The silk fibroin particles were extruded through 14Gneedles without no or no incidence of clogging. The rate of compressingthe plunger of the syringe was 5.5 mm/s, which corresponds to extrusionof 1 mL of material in 10 seconds.

FIGS. 9A-9D show particle physical characterization and extrusion data.FIG. 9A is a SEM image of porous silk fibroin particles according to oneembodiment described herein. Average particle diameter is 500-600 μm.Scale bar is 200 μm. FIG. 9B is a graph showing pore size distributionof the porous silk fibroin sponge by mercury intrusion porosimetry.Lyophilized silk fibroin sponge have an average pore diameter of 40-50μm (e.g., 44 μm), with 93% total porosity. Pores as small as 4 micronsin diameter or as large as 200 microns in diameter were also detected,but at very low frequency. “-dV/dlog(D)” is a measure of infiltratedmercury into silk fibroin pores. It is contemplated that particlesreduced from the silk fibroin sponge have comparable pore size. FIG. 9Cshows extrusion forces of formulations comprising prior art particles(e.g., HFIP, salt-leached porous particles, and aqueous derivednon-porous particles) at 20% and 50% v/v concentrations in a silk-basedgel carrier. The formulations were extruded through 1 mL syringes with a14 or 16G needle. The full 1 mL volume was unable to be extruded due tofrequent clogging at the needle. Clogging is denoted by extrusion forcesexceeding 100N. FIG. 9D shows compositions comprising aqueous—derivedporous silk fibroin particles according to some embodiments describedherein in lipoaspirate. Such formulations were shown to be injectablevia 1 mL syringes with a 14 or 16G needle when mixed with lipoaspirateat volume concentrations up to 50% v/v. Compared to lipoaspirate only(darkest curve), silk particle/lipoaspirate mixtures were extruded atsimilar forces within the optimal range of 15-30N.

FIG. 10 shows histological analysis of silk fibroin particle implantsafter 12 month subcutaneous implantation in rats. Silk fibroin particlesallowed infiltration of surrounding macrophages into the porousstructure. Minimal immune response was detected throughout 12 months.Scale bar=250 μm. Arrows indicate silk fibroin particles.

FIG. 11 is a graph showing in vivo degradation rate of silk fibroinparticles alone according to some embodiments described herein uponimplantation into animals as described in FIG. 10 . The in vivodegradation rate was measured as a change in initial implant volume overtime.

FIG. 12A shows SEM analysis of a cross-section of a silk fibroin sponge,depicting lamellar pore formation and the length and width of the pores.SEM analysis of silk fibroin sponge cross-sections after post-treatmentand air-hood drying was performed. Contrast was manipulated such thatsilk fibroin are presented as white pixels and pores are presented asblack pixels. The aspect ratio (AR) of pores (AR=length (L)/width (W))was determined using image analysis software. An AR value of 1 indicatesa perfect circular cross-section. In some embodiments, the silk fibroinsponges have AR values near 1. FIGS. 12B-12C show the original image(left), contrast-enhanced image (middle), and ellipses fit image (right)of desirable rounded pore formation (FIG. 12B) and undesirable lamellarpore formation (FIG. 12C). FIG. 12D is a graph showing the aspect ratiodistribution of pores based on the cross-section of the silk fibroinsponge with pores of rounded morphology (desirable) or lamellarmorphology (undesirable).

FIGS. 13A-13F show additional experimental data showing aspect ratios ofpores present in the silk fibroin sponge produced by the methoddescribed in the International Patent Publication No. WO 2016/145281.The aspect ratios were determined from SEM images of cross sections ofsilk fibroin sponges. FIGS. 13A and 13D are SEM images of cross-sectionsof the silk fibroin sponges. Contrast was manipulated using imageanalysis tool such that silk fibroin are presented as white pixels andpores are presented as black pixels. FIGS. 13B and 13E show the outlineof the pores by ellipses fit. FIGS. 13C and 13F are distribution graphsshowing aspect ratios of the pores.

FIGS. 14A-14F show additional experimental data showing aspect ratios ofpores present in the silk fibroin material produced by the methoddescribed in the International Patent Publication No. WO 2013/071123.The aspect ratios were determined from SEM images of cross sections ofsilk fibroin materials. FIGS. 14A and 14D are SEM images ofcross-sections of the silk fibroin sponges. Contrast was manipulatedusing image analysis tool such that silk fibroin are presented as whitepixels and pores are presented as black pixels. FIGS. 14B and 14E showthe outline of the pores by ellipses fit. FIGS. 14C and 14F aredistribution graphs showing aspect ratios of the pores.

FIGS. 15A-15C show compressive mechanical analysis of silk fibroinmaterials according to some embodiments described herein. In someembodiments, silk fibroin particles are produced from silk fibroinsponges. The silk fibroin sponges were produced from the methoddescribed in the International Patent Publication No. WO 2016/145281.FIG. 15A shows stress-strain profile of the silk fibroin sponges inhydrated state. The elastic modulus (at 6-10% axial strain) of the silkfibroin sponges was found to be 72.4±5.2 kPa. FIG. 15B shows compressiverecovery for the silk fibroin sponges in hydrated state. FIG. 15C showsthe compressive mechanics measured from a population of silk fibroinparticles according to some embodiments described herein.

FIGS. 16A-16B is a set of graphs showing extrusion force data using a 1mL syringe (21 gauge needle) for compositions comprising a crosslinkedHA carrier, alone or in combination with silk fibroin particles,according to one set of embodiments described herein. The silk fibroinparticles were about 355 to about 425 microns in diameter, and wereabout 40% v/v when mixed with crosslinked HA gel. FIG. 16A: extrusion ofcrosslinked HA gel carrier only, FIG. 16B: extrusion of crosslinked HAwith silk fibroin particles.

FIGS. 17A-17B is a set of graphs showing extrusion force data using a 3mL syringe appended to a 18 gauge tulip cannula for compositionscomprising a crosslinked HA carrier in combination with silk fibroinparticles, according to some embodiments described herein. The silkfibroin particles were about 425 to about 500 microns in diameter, andwere about 40% v/v when mixed with crosslinked HA gel. FIG. 17A:extrusion of the composition in which crosslinked HA was prepared with acrosslinking agent (CA), e.g., BDDE, and hyaluronic acid disaccharides(HAD) in a CA:HAD mole ratio of about 22%. FIG. 17B: extrusion of thecomposition in which crosslinked HA was prepared with a crosslinkingagent (CA), e.g., BDDE, and hyaluronic acid disaccharides (HAD) in aCA:HAD mole ratio of about 30%.

FIG. 18 is a graph showing extrusion force data using 1 mL syringe withdifferent gauge needle sizes for compositions comprising a crosslinkedHA and silk fibroin particles according to one set of embodimentsdescribed herein. The silk fibroin particles were about 355 to about 425microns in diameter, and were about 40% v/v when mixed with crosslinkedHA gel.

FIG. 19 is a graph showing extrusion force data using 1 mL syringe witha 21 gauge needle for compositions comprising a crosslinked HA and silkfibroin particles in varying amounts according to some embodimentsdescribed herein. The silk fibroin particles were about 355 to about 425microns in diameter, and were mixed with crosslinked HA gel in varyingamounts from about 40% v/v to about 60% v/v silk fibroin particles.

FIGS. 20A-20D is a set of graphs showing rheometry data describing theshear properties for compositions comprising a crosslinked HA carrier incombination with silk fibroin particles according to one set ofembodiments described herein. The silk fibroin particles were about 355to about 425 microns in size, and 40% v/v silk fibroin particles weremixed with crosslinked HA gel. FIG. 20A: storage modulus (G′) and lossmodulus (G″) of the composition were measured as a function ofoscillatory frequency sweeps from 0.1-10 Hz. FIG. 20B: dynamic viscositywas measured as a function of oscillatory frequency sweeps from 0.1-10Hz. FIG. 20C: storage modulus (G′) and loss modulus (G″) of thecomposition were measured as a function of strain from 0.1-100. FIG.20D: elasticity of the composition was measured as a function offrequencies of 1 and 10 Hz.

FIG. 21 is an illustration of an exemplary method to determine crosslinkdensity in a crosslinked HA gel. Protocol adapted from: Kenne et al.Carbohydrate Polymers (2013) 91: 410-418.

FIG. 22 depicts a device for delivering a composition to a subjectaccording to some aspects.

FIG. 23 depicts an enlargement of a distal portion of the device of FIG.22 showing a needle of the device.

FIG. 24 depicts an enlarged view of the needle of FIG. 23 .

FIG. 25 is a cross-section of the needle of FIG. 24 .

FIG. 26A is a top view of the needle of FIG. 24 .

FIG. 26B is a side view of the needle of FIG. 24 .

FIG. 27 depicts an enlargement of a distal portion of the device of FIG.22 showing an angled bend in tubing of the device.

FIG. 28 depicts a cross-section of the tubing of the device, showingthat the tubing includes an inner tube and an outer sheath tube.

FIG. 29 depicts a needle coupled to a needle sheath according to oneembodiment.

FIG. 30A depicts a side view of the needle and needle sheath assembly ofFIG. 29 .

FIG. 30B depicts a top view of the needle and needle sheath assembly ofFIG. 29 .

FIG. 31A depicts a perspective view of the needle sheath of FIG. 29 .

FIG. 31B depicts a side view of the needle sheath of FIG. 31A.

FIG. 32 depicts an enlarged view of a handle of the device of FIG. 22 .

FIG. 33A depicts an enlarged view of a leading portion of the handle ofFIG. 32 .

FIG. 33B depicts a top down view of the leading portion of the handle ofFIG. 33A.

FIG. 34A depicts an enlarged view of a back portion of the handle ofFIG. 32 .

FIG. 34B depicts a top down view of the back portion of the handle ofFIG. 34A.

FIG. 35 depicts a perspective view of a connecting tube.

FIG. 36 is a chart showing rheology data for certain silk/HAcompositions after ex vivo injection into porcine tissue.

FIG. 37 is a chart showing the elasticity of certain silk/HAcompositions after ex vivo injection into porcine tissue.

FIG. 38 is a micrograph showing a sample obtained 6 months afterinjection of a silk/HA material into a rat, in accordance with certainembodiments.

FIG. 39 is a micrograph showing a sample obtained 6 months afterinjection of a CaHA material into a rat, in accordance with certainembodiments.

FIGS. 40A and 40B are micrographs showing samples obtained 12 monthsafter injection of a silk/HA material into a rat, in accordance withcertain embodiments.

FIGS. 41A and 41B are micrographs showing samples obtained 12 monthsafter injection of HA into a rat, in accordance with certainembodiments.

FIG. 42 is a photograph of a catheter, in accordance with certainembodiments.

FIG. 43 is a photograph showing an injection of a silk/HA compositioninto a canine vocal fold, in accordance with certain embodiments.

FIG. 44 shows micrographs of the immediate post injection appearance andthe 3 months post injection appearance of augmentation in a canine modelfor a silk/HA composition, in accordance with certain embodiments.

FIG. 45 shows micrographs of the immediate post injection appearance andthe 3 months post injection appearance of augmentation in a canine modelfor a CaHA material, in accordance with certain embodiments.

FIG. 46 is a schematic depicting a location at which a silk/HAcomposition may be delivered, in accordance with certain embodiments.

FIGS. 47-49 are micrographs showing canine vocal folds two months afterinjection of a silk/HA composition, and canine vocal folds into which asilk/HA composition has not been injected, in accordance with certainembodiments.

FIGS. 50A-50B show a pore size distribution (FIG. 50A) of silk fibroinparticles according to one set of embodiments described herein, asdetermined by scanning electron microscopy and image analysis, with arepresentative image of the cross-section of a silk fibroin particle(FIG. 50B). The “pore size” in the graph refers to circle equivalentdiameter.

FIG. 51A-51B show a particle size distribution (FIG. 51A) of silkfibroin particles according to one set of embodiments described herein,as determined by laser diffraction analysis, with a representative imageof silk fibroin particles (FIG. 51B).

FIG. 52 is the pore aspect ratio distribution of silk fibroin particlesaccording to one set of embodiments described herein, as determined byscanning electron microscopy and image analysis. The pore shape ischaracterized by an aspect ratio, which is a ratio of pore major axis topore minor axis.

FIG. 53 is the pore circularity distribution of silk fibroin particlesaccording to one set of embodiments described herein, as determined byscanning electron microscopy and image analysis. The pore shape ischaracterized by a circularity value, which is determined as:(4πA_(pore)/P_(pore) ²), where A_(pore) is the average cross-sectionarea of the pores and P_(pore) is the average perimeter forming theboundary of the cross-section area of the pores.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Some aspects of the present disclosure provide injectable compositionscomprising a highly crosslinked matrix carrier (e.g., highly crosslinkedhyaluronic acid, but not limited to such) and biocompatible particlesdispersed therein, methods of manufacturing and using such compositions,and delivery devices and kits for applying such compositions. Suchcompositions are generally stiffer and more resistant to in vivodegradation than those comprising a low-crosslinked matrix carrier, yetthese compositions are injectable through a needle with smootherextrusion profiles than those observed for the same concentration ofhighly-crosslinked carrier alone without particles (e.g., highlycrosslinked hyaluronic acid alone).

In some aspects, the present disclosure provides novel silk fibroinparticles and compositions comprising the same, and a carrier such that(i) the particles and/or compositions exhibit little or minimal plasticdeformation; (ii) the particles and/or compositions are biocompatiblewith cells and/or tissues (e.g., soft tissues) with minimalcomplications such as formation of granulomas at tissue injection site;(iii) the particles and/or compositions are tunable to match as close aspossible at least one or more mechanical properties (e.g., elasticity)of tissue to be treated; (iv) the particles and/or compositions aretunable to degrade at a rate appropriate for a particular biomedicalapplication (e.g., are tunable to degrade at a rate that is slow enoughto provide a long lasting bulking effect, e.g., can fill up wrinkles forcosmetic purposes or bulk vocal cord so as to minimize frequenttreatment); and (v) the particles and/or compositions are injectablewith low extrusion forces. The compositions described herein can beadjusted for any suitable biomedical applications such as soft tissueaugmentation and/or regeneration (e.g., breast reconstruction,lumpectomy reconstruction, correction of glottic (vocal cord)insufficiency, treatment of urinary incontinence, injectable fillers anddermal fillers, e.g., for wrinkles), wound sealing or clotting, and/ordrug delivery such as controlled release applications. Methods of usingthese silk fibroin particles and/or compositions as well as deliverydevices and kits for applying such compositions are also providedherein.

Appropriate combination of silk fibroin particles and a carrier, asdescribed herein, provides advantages of material and degradationtunability of the compositions herein as well as clinically acceptableextrusion force of the compositions. For example, addition of silkfibroin particles prolongs a bulking effect of a composition injectedinto a tissue, without increasing the concentration and/or crosslinkdensity of the carrier to achieve the same effect. Generally, increasingthe concentration and/or crosslink density of a carrier would result inan undesirable increase in the extrusion force during the course ofinjection. However, the compositions described herein may be formulatedto have favorable extrusion characteristics while also providingcomparable soft tissue bulking. Accordingly, the compositions describedherein may provide desirable material and mechanical properties withoutadversely affecting their injectability.

Injectable Compositions Comprising a Crosslinked Matrix Carrier andParticles

One aspect provided herein relates to an injectable compositioncomprising a matrix carrier (e.g., crosslinked or non-crosslinked) andparticles, wherein a standard deviation of extrusion force of thecomposition through a 18-30 (e.g., 18, 19, 20, 21, 22, 23, 24, 25, 26,27, 28, 29, or 30) gauge needle into air, as determined between about50% extrusion volume and about 90% extrusion volume, is at least about30% lower (including, e.g., at least about 20% lower, at least about 10%lower, at least about 5% lower, at least about 1% lower) than a standarddeviation of extrusion force of a corresponding matrix carrier alone(e.g., without particles) through a needle of the same gauge. In someembodiments, the matrix carrier is crosslinked.

Another aspect provided herein relates to an injectable compositioncomprising a matrix carrier (e.g., crosslinked or non-crosslinked) andparticles, wherein a reduction in stiffness of the composition asmeasured between about 10% strain and about 90% strain is at least about10% larger, at least about 20% larger, at least about 30% larger, atleast about 40% larger, at least about 50% larger (including, e.g., atleast about 60% larger, at least about 70% larger, at least about 80%larger, at least about 90% larger, at least about 1.1-fold larger, atleast about 1.5-fold larger, at least about 2-fold larger, at leastabout 3-fold larger, at least about 4-folder larger) than a change instiffness of the corresponding matrix carrier alone (e.g., withoutparticles) as measured between the about 10% strain and about 90%strain. In some embodiments, a reduction in stiffness of the compositionas measured between about 10% strain and about 90% strain is about5-fold or less, about 4-fold or less, about 3-fold or less, about 2-foldor less, or about 1-fold or less) than a change in stiffness of thecorresponding matrix carrier alone (e.g., without particles) as measuredbetween the about 10% strain and about 90% strain. Combinations of theabove-referenced ranges are also possible. In some embodiments, thematrix carrier is crosslinked.

The inventors unexpectedly discovered that addition of silk fibroinparticles to a viscous carrier, e.g., a crosslinked matrix carrier suchas crosslinked hyaluronic acid, improves the smoothness of the extrusionprofile, compared to the viscous carrier without the silk fibroinparticles, all other factors being equal. In addition, the inventorsdiscovered that such compositions provide the same or similar immediatesoft tissue bulking and are easily sculpted, but are longer-lasting andpromote regeneration of soft tissue into the porous silk fibroinparticles while the carrier slowly degrades. For example, Example 9shows that when silk fibroin particles were combined with a highlycrosslinked hyaluronic acid carrier, the addition of silk fibroinparticles improved smoothness of the extrusion force profile. Thecrosslinked hyaluronic acid (HA) carrier by itself typically has anextrusion profile that is not as smooth, e.g., the extrusion forcefluctuates over the course of the injection as shown in FIG. 16A.Example 10 shows that the addition of silk fibroin particles to acrosslinked HA carrier reduces the strain required to cause thecomposition to yield to flow, while the crosslinked HA alone is morestrain-resistant and does not yield as early as the silkfibroin/crosslinked HA composition. The strain-induced yielding propertyobserved in the silk fibroin/crosslinked HA composition may aid in theability of the material to naturally spread better once implanted orinjected, conforming to difficult geometries, e.g., of a void space orwound, better than crosslinked HA gels alone. It may also allow thematerial to flow better, e.g., smoother (compared to crosslinked HAcarrier without silk fibroin particles), when extruded through, forexample, a 21 gauge needle, resulting in a smoother extrusion profile.It was also observed that crosslinked HA gels alone result in tough gelsthat are tacky, but do not cohere well to itself in a bulk volume (e.g.,1 cc extruded). The compositions comprising crosslinked HA and silkfibroin particles according to some embodiments described herein, on theother hand, exhibit high cohesion and may be sculpted easily.Accordingly, by addition of an appropriate amount of silk fibroinparticles (e.g., a specific volume ratio of silk fibroin particles to acarrier as described herein, e.g., about 30% v/v to about 60% v/v silkfibroin particles), a viscous carrier with a high crosslink density(e.g., highly crosslinked HA) can be used to benefit from longer in vivolifetime while maintaining a smooth extrusion force profile that issuitable for injection.

The viscous carrier may be crosslinked or non-crosslinked. In someembodiments, the viscous carrier is a crosslinked matrix carrier. Thecrosslinked matrix carrier may comprise crosslinked glycosaminoglycanpolymers (e.g., crosslinked hyaluronic acid), crosslinked extracellularmatrix protein polymers (e.g., crosslinked collagen, crosslinkedelastin, and/or crosslinked fibronectin), crosslinked polysaccharides(e.g., crosslinked cellulose), crosslinked fibrous protein polymers, ora combination of two or more thereof. In one set of embodiments of thecompositions or injectable compositions described herein, thecrosslinked matrix carrier is crosslinked hyaluronic acid.

In some embodiments, the viscous carrier is a non-crosslinked(interchangeably used with “uncrosslinked”) matrix carrier. Examples ofuncrosslinked matrix carriers include, but are not limited to HA,uncrosslinked chondroitin sulfate polymers, uncrosslinked dermatansulfate polymers, uncrosslinked keratan sulfate polymers, uncrosslinkedheparan polymers, uncrosslinked heparan sulfate polymers, uncrosslinkedhyaluronan polymers, uncrosslinked glycosaminoglycan polymers,uncrosslinked elastin and/or fibronectin, and any combinations thereof.

Accordingly, one aspect relates to an injectable composition comprisingcrosslinked hyaluronic acid (HA) and particles, wherein the compositionis characterized in that a standard deviation of extrusion force of thecomposition through a 18-30 (e.g., 18, 19, 20, 21, 22, 23, 24, 25, 26,27, 28, 29, or 30) gauge needle into air, as determined between about50% extrusion volume and about 90% extrusion volume, is less than about40% of an average extrusion force for the corresponding range of theextrusion volume.

In some embodiments of any compositions or injectable compositionsdescribed herein (e.g., including a crosslinked matrix carrier andparticles), the standard deviation of extrusion force of the compositionthrough a 18-30 (e.g., 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,or 30) gauge needle into air, as determined between about 50% extrusionvolume and about 90% extrusion volume, is less than about 35%, less thanabout 30%, less than about 25%, less than about 20%, less than about15%, less than about 10%, less than about 5%, or less than about 1%, ofan average extrusion force for the corresponding range of the extrusionvolume (i.e., about 50%-about 90% extrusion volume). In someembodiments, the standard deviation of extrusion force of thecomposition through a 18-30 (e.g., 18, 19, 20, 21, 22, 23, 24, 25, 26,27, 28, 29, or 30) gauge needle into air, as determined between about50% extrusion volume and about 90% extrusion volume, is at least about0.1%, at least about 0.5%, at least about 1%, at least about 5%, atleast about 10%, at least about 15%, or at least about 20%, of anaverage extrusion force for the corresponding range of the extrusionvolume (i.e., about 50%-about 90% extrusion volume). Combinations of theabove-referenced ranges are also possible. For example, in someembodiments, the standard deviation of extrusion force of thecomposition through a 18-30 (e.g., 18, 19, 20, 21, 22, 23, 24, 25, 26,27, 28, 29, or 30) gauge needle into air, as determined between about50% extrusion volume and about 90% extrusion volume, is about 0.1% toabout 40%, or about 1% to about 20%, or about 1% to about 15%, of anaverage extrusion force for the corresponding range of the extrusionvolume (i.e., about 50%-about 90% extrusion volume). For example, asshown in FIG. 16B, the standard deviation of extrusion force of thecomposition (according to one set of embodiments described herein)through a 21 gauge needle into air, as determined between about 50%extrusion volume and about 90% extrusion volume, is about 1% to about15%, of an average extrusion force for the corresponding range of theextrusion volume (i.e., about 50%-about 90% extrusion volume). Bycontrast, as shown in FIG. 16A for crosslinked HA gel alone, thestandard deviation of extrusion force through a 21 gauge needle intoair, as determined between about 50% extrusion volume and about 90%extrusion volume, is at least about 10% or higher of an averageextrusion force for the corresponding range of the extrusion volume(i.e., about 50%-about 90% extrusion volume).

Also provided herein is an injectable composition comprising crosslinkedHA and particles, wherein the composition is characterized in that astiffness of the composition decreases with respect to increasingstrain. For instance, the injectable composition comprising crosslinkedHA and particles may be characterized in that a stiffness of thecomposition is decreased by at least about 10% as measured within apre-determined range of strain (e.g., about 0.1% strain to about 1%strain, or about 0.1% strain to about 10% strain, or about 0.1% strainto about 100% strain, or about 10% strain and about 90% strain). Thestiffness values may be measured at the endpoints of the pre-determinerange (e.g., at about 0.1% strain and at about 100% strain for apre-determined range of about 0.1% strain and about 100% strain) and thepercent difference in the stiffness at these two points can be used forthe calculation, based on the value of stiffness at the lowest % strain(e.g., 0.1% strain). The stiffness of the composition may be determinedby shear storage modulus (G′) of the composition.

In some embodiments of any compositions or injectable compositionsdescribed herein (e.g., including a crosslinked matrix carrier andparticles), the stiffness of the composition is decreased by at leastabout 15%, at least about 20%, at least about 30%, at least about 40%,at least about 50%, at least about 60%, at least about 70%, at leastabout 80%, at least about 90%, or higher, as measured between about 0.1%strain and about 1% strain. In some embodiments, the stiffness of thecomposition is decreased by no more than about 95%, no more than about90%, no more than about 80%, no more than about 70%, no more than about60%, no more than about 50%, no more than about 40%, no more than about30%, or no more than about 20%, as measured between about 0.1% strainand about 1% strain. Combinations of the above-referenced ranges arealso possible. In some embodiments, the stiffness of the composition isdecreased by about 10% to about 90% or about 15% to about 80%, or about10% to about 40% or about 10% to about 30%, as measured between about0.1% strain and about 1% strain.

In some embodiments of any compositions or injectable compositionsdescribed herein (e.g., including a crosslinked matrix carrier andparticles), the stiffness of the composition is decreased by at leastabout 15%, at least about 20%, at least about 30%, at least about 40%,at least about 50%, at least about 60%, at least about 70%, at leastabout 80%, at least about 90%, or higher, as measured between about 0.1%strain and about 10% strain. In some embodiments, the stiffness of thecomposition is decreased by no more than about 95%, no more than about90%, no more than about 80%, no more than about 70%, no more than about60%, no more than about 50%, no more than about 40%, no more than about30%, or no more than about 20%, as measured between about 0.1% strainand about 10% strain. Combinations of the above-referenced ranges arealso possible. In some embodiments, the stiffness of the composition isdecreased by about 10% to about 90% or about 15% to about 80%, or about10% to about 40% or about 10% to about 30%, as measured between about0.1% strain and about 10% strain.

In some embodiments of any compositions or injectable compositionsdescribed herein (e.g., including a crosslinked matrix carrier andparticles), the stiffness of the composition is decreased by at leastabout 15%, at least about 20%, at least about 30%, at least about 40%,at least about 50%, at least about 60%, at least about 70%, at leastabout 80%, at least about 90%, or higher, as measured between about 0.1%strain and about 100% strain. In some embodiments, the stiffness of thecomposition is decreased by no more than about 95%, no more than about90%, no more than about 80%, no more than about 70%, no more than about60%, no more than about 50%, no more than about 40%, no more than about30%, or no more than about 20%, as measured between about 0.1% strainand about 100% strain. Combinations of the above-referenced ranges arealso possible. In some embodiments, the stiffness of the composition isdecreased by about 10% to about 90% or about 15% to about 80%, or about10% to about 40% or about 10% to about 30%, as measured between about0.1% strain and about 100% strain.

In some embodiments of any compositions or injectable compositionsdescribed herein (e.g., including a crosslinked matrix carrier andparticles), the stiffness of the composition is decreased by at leastabout 15%, at least about 20%, at least about 30%, at least about 40%,at least about 50%, at least about 60%, at least about 70%, at leastabout 80%, at least about 90%, or higher, as measured between about 10%strain and about 90% strain. In some embodiments, the stiffness of thecomposition is decreased by no more than about 95%, no more than about90%, no more than about 80%, no more than about 70%, no more than about60%, no more than about 50%, no more than about 40%, no more than about30%, or no more than about 20%, as measured between about 10% strain andabout 90% strain. Combinations of the above-referenced ranges are alsopossible. In some embodiments, the stiffness of the composition isdecreased by about 10% to about 90% or about 15% to about 80%, or about10% to about 40% or about 10% to about 30%, as measured between about10% strain and about 90% strain.

As shown in FIG. 20C, the stiffness of the composition according to oneset of embodiments described herein (a) is decreased by about 25%, asmeasured between about 0.1% strain and about 1% strain; (b) is decreasedby about 35-40%, as measured between about 0.1% strain and about 10%strain; (c) is decreased by about 75-80% as measured between about 0.1%strain and about 100% strain; or (d) is decreased by about 30-35% asmeasured between about 10% strain and about 90% strain. By contrast, thestiffness of a corresponding crosslinked carrier alone (e.g.,crosslinked HA carrier alone) is substantially constant until about 40%strain. The stiffness of the crosslinked carrier alone (e.g.,crosslinked HA carrier alone) is decreased by only about 10-15%, asmeasured between about 0.1% strain and about 100% strain.

In some embodiments of any compositions or injectable compositionsdescribed herein (e.g., including a crosslinked matrix carrier andparticles), the average force of extruding 1 mL of the compositionthrough a 18-30 gauge needle (e.g., 18, 19, 20, 21, 22, 23, 24, 25, 26,27, 28, 29, or 30 gauge) is at least about 30%, at least about 40%, atleast about 50%, at least about 60%, at least about 70%, lower than thatof extruding 1 mL of the crosslinked matrix carrier (e.g., crosslinkedHA) alone through a needle of the same gauge number. In someembodiments, the average force of extruding 1 mL of the compositionthrough a 18-30 gauge needle is no more than 80%, no more than 70%, nomore than 60%, no more than 50%, no more than 40%, or no more than 30%,lower than that of extruding 1 mL of the crosslinked matrix carrier(e.g., crosslinked HA) alone through a needle of the same gauge number.Combinations of the above-referenced ranges are also possible. Forexample, in some embodiments of any one of compositions or injectablecompositions provided herein, the average force of extruding 1 mL of thecomposition through a 18-30 gauge needle is about 30% to about 80%, orabout 40% to about 70%, lower than that of extruding 1 mL of thecrosslinked matrix carrier (e.g., crosslinked HA) alone through a needleof the same gauge number.

In some embodiments involving the compositions or injectablecompositions described herein, the crosslinked matrix carrier (e.g.,crosslinked hyaluronic acid) may have a concentration of at least about0.1% (w/v), at least about 0.5% (w/v), at least about 1% (w/v), at leastabout 2% (w/v), at least about 3% (w/v), at least about 4% (w/v), atleast about 5% (w/v), at least about 6% (w/v), at least about 7% (w/v),at least about 8% (w/v), at least about 9% (w/v), at least about 10%(w/v). In some embodiments, the crosslinked matrix carrier (e.g.,crosslinked hyaluronic acid) may have a concentration of no more than10% (w/v), no more than 9% (w/v), no more than 8% (w/v), no more than 7%(w/v), no more than 6% (w/v), no more than 5% (w/v), no more than 4%(w/v), no more than 3% (w/v), no more than 2% (w/v), no more than 1%(w/v), no more than 0.5% (w/v), or no more than 0.1% (w/v). Combinationsof the above-referenced ranges are also possible. For example, in someembodiments, the crosslinked matrix carrier (e.g., crosslinked HA) havea concentration of about 0.1% (w/v) to about 10% (w/v) or 0.5% (w/v) toabout 10% (w/v), or 1% (w/v) to about 10% (w/v), or about 2% (w/v) toabout 8% (w/v), or about 3% (w/v) to about 6% (w/v).

In addition to the needle gauge size and/or concentration of thecrosslinked matrix carrier (e.g., crosslinked HA), the average extrusionforce of the compositions of any aspects described herein may also varywith the crosslink density of a crosslinked matrix carrier. As usedherein, the term “crosslink density” describes the final crosslinkdensity of a crosslinked carrier, which is determined as a ratio of thetotal number of molecules (or moles) of a crosslinking agentincorporated into the crosslinked carrier to the total number ofrepeating entity molecules (or moles) of the carrier present in thecrosslinked carrier, multiplied by 100. For example, the crosslinkdensity of crosslinked hyaluronic acid is a ratio of the total number ofmolecules (or moles) of a crosslinking agent (e.g., BDDE) incorporatedinto the crosslinked HA to the total number of disaccharide units(repeating entity molecules) of hyaluronic acid present in thecrosslinked HA, multiplied by 100. The crosslink density of acrosslinked carrier can be determined, for example, by proton nuclearmagnetic resonance (1 H NMR) as described in Example 11. Examples ofcross-linking agents include, but are not limited to epichlorohydrin,divinyl sulfone, 1,4-bis(2,3-epoxypropoxy)butane (or1,4-bisglycidoxybutane or 1,4-butanediol diglycidyl ether (BDDE)),1,2-bis(2,3-epoxypropoxy)ethylene,1-(2,3-epoxypropyl)-2,3-epoxycyclohexane, and aldehydes such asformaldehyde, glutaraldehyde and crotonaldehyde, taken by themselves orin a mixture. In one embodiment, the cross-linking agent comprises1,4-butanediol diglycidyl ether (BDDE).

In one set of embodiments described herein, the crosslinked carrier(e.g., a crosslinked HA) has a crosslink density of at least about 4 mol%, at least about 5 mol %, at least about 6 mol %, at least about 7 mol%, at least about 8 mol %, at least about 9 mol %, at least about 10 mol%, at least about 11 mol %, at least about 12 mol %, at least about 13mol %, at least about 14 mol %, at least about 15 mol %, at least about16 mol %, at least about 17 mol %, at least about 18 mol %, at leastabout 19 mol %, at least about 20 mol %, at least about 25 mol %, atleast about 30 mol %, at least about 35 mol %, at least about 40 mol %,or higher. In some embodiments, the crosslinked carrier (e.g., acrosslinked HA) has a crosslink density of no more than about 40 mol %,no more than about 35 mol %, no more than about 30 mol %, no more thanabout 25 mol %, or no more than about 20 mol %. Combinations of theabove-referenced ranges are also possible. For example, in someembodiments, the crosslinked carrier (e.g., a crosslinked HA) may have acrosslink density of about 4 mol % to about 30 mol %, about 4 mol % toabout 25 mol %, or about 4 mol % to about 20 mol %.

In one set of embodiments of the compositions or injectable compositionsdescribed herein where the crosslinked matrix carrier (e.g., crosslinkedHA) has a crosslink density of about 4 mol % to about 30 mol %(including combinations of the above-referenced ranges), the compositionis characterized in that an average force of extruding about 1 mL of thecomposition through a 18-30 gauge needle (e.g., 18, 19, 20, 21, 22, 23,24, 25, 26, 27, 28, 29, or 30 gauge) into air is less than 60 N,including, for example less than 50 N, less than 40 N, less than 30 N,less than 20 N, less than 15 N, less than 10 N, or less than 5 N. Insome embodiments, the composition is characterized in that an averageforce of extruding about 1 mL of the composition through a 18-30 gaugeneedle (e.g., 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30gauge) into air is equal to or more than 5 N, equal to or more than 10N, equal to or more than 15 N, equal to or more than 20 N, equal to ormore than 30 N, equal to or more than 40 N, equal to more than 50 N,equal to or more than 60 N. Combinations of the above-referenced rangesare also possible. For example, in some embodiments, the composition ischaracterized in that an average force of extruding about 1 mL of thecomposition through a 18-30 gauge needle (e.g., 18, 19, 20, 21, 22, 23,24, 25, 26, 27, 28, 29, or 30 gauge) into air is about 5 N to about 60N, about 10 N to about 50 N, or about 15 N to about 50 N, or about 20 Nto about 50 N, or about 5 N to about 60 N.

Generally, the extrusion force is lower if needles with smaller gaugenumbers (corresponding to larger needle diameters) are used; and theextrusion force is higher if needles with higher gauge numbers(corresponding to smaller needle diameters) are used.

As used herein, the term “average force of extruding” or “averageextrusion force” generally refers to the average force required tosustain extrusion of a composition described herein through a needle. Inother words, in an extrusion force profile (i.e., a graph of a force orpressure required to extrude a composition as a function of extrudedvolume or length), the “average extrusion force” is determined from aportion of the graph where sustained extrusion occurs, typicallypreceded by an initial increasing force required to displace a plunger(plunger break-loose force). As used herein, the term “sustainedextrusion” refers to a substantially continuous extrusion of a materialthrough a needle with a substantially constant force, after the motionof the plunger is initiated and before the plunger presses against theend of a syringe body. In some embodiments, the sustained extrusionrefers to a portion of an extrusion force profile (i.e., a graph of aforce or pressure required to extrude a composition as a function ofextruded volume or length) where the standard deviation of the extrusionforce of a material as determined from the profile portion is less thanabout 40% (including, e.g., less than about 30%, less than about 25%,less than about 20%, less than about 15%, less than about 10%, or lessthan about 5%) of the average extrusion force determined from the sameprofile portion. In one set of embodiments described herein, thesustained extrusion refers to a portion of an extrusion force profilebetween about 50% extrusion volume and about 90% extrusion volume. Thesmaller the standard deviation of the extrusion force is, the smootherthe profile of the sustained extrusion is, e.g., represented by arelatively smooth plateau. On the other hand, the profile of thesustained extrusion appears less smooth, e.g., a spiky profile, when thestandard deviation of the extrusion force is too large, e.g., more than50% of the average extrusion force for the corresponding range ofextrusion volume. In some embodiments, the average extrusion force ismeasured based on a 1 mL of a composition described herein through a 21gauge needle into air (e.g., under atmospheric pressure) at across-speed of 5.5 mm/seconds. In some embodiments, the term “averageextrusion force” may be equivalent to “dynamic glide force” as used inthe art.

In some embodiments, the force required to sustain extrusion of any oneof the compositions described herein at any point during the course ofinjection deviates from the average extrusion force by no more thanabout 40% or lower, including, no more than about 30%, no more thanabout 25%, no more than about 20%, no more than about 15%, no more thanabout 10%, no more than about 5% or lower.

In some embodiments involving the compositions or injectablecompositions described herein, the particles and the crosslinked matrixcarrier (e.g., crosslinked HA) are present in a volume ratio of about5:95 to about 95:5.

The crosslinked matrix carrier (e.g., crosslinked HA) and the particlescan be present in any volume ratio that yields properties of thecompositions suitable for the need of a particular application. In someembodiments of any one of the compositions or injectable compositionsdescribed herein, the total amounts of crosslinked matrix carrier (e.g.,crosslinked HA) and the particles are in a volume ratio (HA: particle)of at least about 5:95, at least about 10:90, at least about 15:85, atleast about 20:80, at least about 25:75, at least about 30:70, at leastabout 35:65, at least about 40:60, at least about 45:55, at least about50:50, at least about 55:45, at least about 60:40, at least about 65:35,at least about 70:30, at least about 75:25, at least about 80:20, atleast about 85:15, at least about 90:10, or at least about 95:5. In someembodiments, the total amounts of crosslinked matrix carrier (e.g.,crosslinked HA) and the particles are in a volume ratio of less than orequal to about 99:1, less than or equal to about 95:5, less than orequal to about 90:10, less than or equal to about 85:15, less than orequal to about 80:20, less than or equal to about 75:25, less than orequal to about 70:30, less than or equal to about 65:35, less than orequal to about 60:40, less than or equal to about 55:45, less than orequal to about 50:50, less than or equal to about 45:55, less than orequal to about 40:60, less than or equal to about 35:65, less than orequal to about 30:70, less than or equal to about 25:75, less than orequal to about 20:80, less than or equal to about 15:85, less than orequal to about 10:90, or less than or equal to about 5:95. Combinationsof the above-referenced ranges are also possible. For example, in someembodiments of any one of the compositions or injectable compositionsdescribed herein, the total amounts of crosslinked matrix carrier (e.g.,crosslinked HA) and the particles are in a volume ratio of about 5:95 toabout 95:5, or about 10:90 to about 90:10, or about 20:80 to about80:20, or about 25:75 to about 75:25, or about 30:70 to about 70:30, orabout 40:60 to about 60:40. In some embodiments, the total amounts ofcrosslinked matrix carrier (e.g., crosslinked HA) and the particles arein a volume ratio of about 50:50; about 40:60; about 30:70; about 25:75;about 20:80, or about 10:90, or as low as about 5:95. In someembodiments, the total amounts of crosslinked matrix carrier (e.g.,crosslinked HA) and the particles are in a volume ratio of about 60:40,about 70:30, about 75:25; about 80:20, about 90:10 or up to about 95:5.

In some embodiments involving the compositions or injectablecompositions described herein where the total amounts of the crosslinkedmatrix carrier (e.g., crosslinked HA) and the particles are in a volumeratio of about 80:20 to about 40:60, an average force of extruding about1 mL of the composition through a 18-21 gauge (e.g., 18, 19, 20, 21gauge) needle into air is about 40 N or lower. Alternatively, an averageforce of extruding about 1 mL of the composition through a 25-30 gauge(e.g., 22, 23, 24, 25, 26, 27, 28, 29, or 30) gauge needle into air isless than 50 N. In some embodiments, when the total amounts of thecrosslinked matrix carrier (e.g., crosslinked HA) and the particles arein a volume ratio of 70:30 to about 50:50, an average force of extrudingabout 1 mL of the composition through a 21 gauge needle into air isabout 40 N or lower. In some embodiments having any of theabove-referenced extrusion forces described herein, the particles mayhave an average particle size of about 300 μm to about 500 μm, or about200 μm to about 600 μm, or less than about 200 μm.

The particles present in any embodiments of the compositions orinjectable compositions described herein may comprise any biocompatiblematerial that is suitable for soft tissue augmentation and/or drugdelivery in vivo. For example, in some embodiments, the particles maycomprise a biocompatible and/or biodegradable polymer, a silk fibroin, apeptide, or any combinations thereof. Examples of biocompatible and/orbiodegradable polymers include, but are not limited to polyethyleneoxide (PEO), polyethylene glycol (PEG), collagen, fibronectin, keratin,polyaspartic acid, polylysine, alginate, chitosan, chitin, hyaluronicacid, pectin, polycaprolactone, polylactic acid, polyglycolic acid,polyhydroxyalkanoates, dextrans, polyanhydrides, polymer, PLA-PGA,polyanhydride, polyorthoester, polycaprolactone, polyfumarate, collagen,chitosan, alginate, hyaluronic acid and other biocompatible and/orbiodegradable polymers. See, e.g., International Application Nos.: WO04/062697; WO 05/012606.

In one set of embodiments of the compositions or injectable compositionsdescribed herein, the particles dispersed in the crosslinked matrixcarrier (e.g., crosslinked HA) are silk fibroin particles, e.g., asknown in the art or as described herein.

While the particles (e.g., silk fibroin particles) described herein canbe of any shape, e.g., a spherical shape, polygonal-shaped,elliptical-shaped, in some embodiments, the particles (e.g., silkfibroin particles) are substantially spherical. In some embodiments, atleast about 80% or higher (including, e.g., at least about 85%, at leastabout 90%, at least about 95%, at least about 98%, or higher, up to100%) of the particles (e.g., silk fibroin particles) in thecompositions described herein are substantially spherical particles. Insome embodiments, the substantially spherical particles have acircularity value of greater than or equal to about 0.65, greater thanor equal to about 0.7, greater than or equal to about 0.8, greater thanor equal to about 0.9, or greater than or equal to about 0.96. In someembodiments, the substantially spherical particles have a circularityvalue of about 0.65 to about 1.0.

In some embodiments, the particles described herein may have an aspectratio of (a ratio of the major axis to the minor axis) of less than orequal to about 4.0, including, e.g., less than or equal to about 3.0,less than or equal to about 2.0, or less than or equal to about 1.0. Insome embodiments, the particles described herein may have an aspectratio of (a ratio of the major axis to the minor axis) of at least about1.0, at least about 1.5, at least about 2.0, at least about 3.0, or atleast about 4.0. Combinations of the above-referenced ranges arepossible. For example, in some embodiments, the particles describedherein may have an aspect ratio of about 1.0 to about 4.0, or about 1.0to about 3.0. To determine the aspect ratio of a particle, thedimensions of the particles can be determined from high-resolutionimages of particles, e.g., scanning electron microscopic images.

The particles (e.g., silk fibroin particles) present in any embodimentof the compositions or injectable compositions described herein canexhibit a distribution of particle sizes. The particle size can varywith a number of factors including, without limitations, the size ofdefect in a tissue (e.g., soft tissue) to be repaired or augmentedand/or desired properties of the particles, e.g., volume retention ordegradation profile. The particles in any one of the compositions orinjectable compositions described herein can have any particle size thatsuits the need of a particular application.

In some embodiments, the particle size of the particles (e.g., silkfibroin particles) is characterized by the average or mean value of asize distribution of the particles. The terms “average” and “mean” areinterchangeably used herein. The average or mean value is generallyassociated with the basis of the size distribution calculation (e.g.,number, surface, or volume). Accordingly, the average size of theparticles (e.g., silk fibroin particles) can correspond to a numberaverage size, a surface average size, or a volume average size. In oneembodiment, the average size refers to volume mean diameter. In someembodiments, the particle size of the particles (e.g., silk fibroinparticles) in any one of the compositions described herein ischaracterized by the mode of a size distribution of particles (e.g.,silk fibroin particles), i.e., the value that occurs most frequently inthe size distribution.

In some embodiments, the average particle size of the particles (e.g.,silk fibroin particles) within a composition or an injectablecomposition described herein is at least about 50 μm, at least about 75μm, at least about 100 μm, at least about 125 μm, at least about 150 μm,at least about 175 μm, at least about 200 μm, at least about 250 μm, atleast about 300 μm, at least about 350 μm, at least about 400 μm, atleast about 450 μm, at least about 500 μm, at least about 550 μm, atleast about 600 μm, at least about 650 μm, at least about 700 μm, atleast about 750 μm, at least about 800 μm, at least about 850 μm, atleast about 900 μm, at least about 950 μm, or at least about 1000 μm. Insome embodiments, the average particle size of the particles (e.g., silkfibroin particles) within a composition or an injectable compositiondescribed herein is less than or equal to about 1000 μm, less than orequal to about 950 μm, less than or equal to about 900 μm, less than orequal to about 850 μm, less than or equal to about 800 μm, less than orequal to about 750 μm, less than or equal to about 700 μm, less than orequal to about 650 μm, less than or equal to about 600 μm, less than orequal to about 550 μm, less than or equal to about 500 μm, less than orequal to about 450 μm, less than or equal to about 400 μm, less than orequal to about 350 μm, less than or equal to about 300 μm, less than orequal to about 250 μm, less than or equal to about 200 μm, less than orequal to about 175 μm, less than or equal to about 150 μm, less than orequal to about 125 μm, less than or equal to about 100 μm, less than orequal to about 75 μm, or less than or equal to about 50 μm. Combinationsof the above-referenced ranges are also possible. In some embodiments,the average particle size of the particles (e.g., silk fibroinparticles) within a composition or an injectable composition describedherein may be about 50 μm to about 1000 μm. In some embodiments, theaverage particle size of the particles (e.g., silk fibroin particles)can be about 250 μm to about 850 μm. In some embodiments, the averageparticle size of the particles (e.g., silk fibroin particles) can beabout 300 μm to about 800 μm. In some embodiments, the average particlesize of the particles (e.g., silk fibroin particles) can be about 400 μmto about 600 μm. In some embodiments, the average particle size of theparticles (e.g., silk fibroin particles) can be about 250 μm to about450 μm. In some embodiments, the average particle size of the particles(e.g., silk fibroin particles) can be about 200 μm to about 500 μm. Insome embodiments, the average particle size of the particles (e.g., silkfibroin particles) can be about 300 μm to about 450 μm. In someembodiments, the average particle size of the particles (e.g., silkfibroin particles) can be about 50 μm to about 200 μm. In someembodiments, the average particle size of the particles (e.g., silkfibroin particles) can be about 75 μm to about 150 μm. In someembodiments, the average particle size of the particles (e.g., silkfibroin particles) can be about 75 μm to about 125 μm. In someembodiments of any average particle size ranges described herein, theaverage particle size of silk fibroin particles may refer to volume meandiameter of silk fibroin particles. In some embodiments, smallerparticles or larger particles may be used provided that the averageforce extruding about 1 mL of the composition through a 18G-30G gaugeneedle into air remains less than 60N (including, e.g., less than 50 N,less than 40 N, or less than 30 N).

Methods for measuring particle size are known to a skilled artisan,e.g., by dynamic light scattering, light obscuration methods (such asCoulter analysis method), or other techniques (such as rheology, andlight or electron microscopy). In some embodiments, laser diffraction isused to measure particle size of the compositions described herein.

In some embodiments, the particles (e.g., silk fibroin particles) cancomprise porous structures, e.g., to mimic the structural morphology ofa native tissue, to modulate the degradation rate/volume retention rateof the particles (e.g., silk fibroin particles), and/or to modulemodulate release profile of an active agent embedded therein, if any. Asused herein, the terms “porous” and “porosity” are generally used todescribe a structure having an interconnected network of pores or voidspaces (which can, for example, be openings, interstitial spaces orother channels) throughout its volume. The term “porosity” is a measureof void spaces in a material, and is a fraction of volume of voids overthe total volume, as a percentage between 0 and 100% (or between 0 and1).

The porous particles (e.g., porous silk fibroin particles) can havepores and/or cervices that are accessible to cells, media, and/orsolutes. The pores can be at the surface of the particles (e.g., silkfibroin particles) and/or within the bulk structure of the particles(e.g., silk fibroin particles). In some embodiments, the porousparticles (e.g., silk fibroin particles) may have an average porosity ofat least about 1%, at least about 3%, at least about 5%, at least about10%, at least about 15%, at least about 20%, at least about 30%, atleast about 40%, at least about 50%, at least about 60%, at least about70%, at least about 80%, at least about 90%, at least about 93%, atleast about 95%, at least about 97%, or higher. In some embodiments, theporous particles (e.g., silk fibroin particles) may have an averageporosity of less than or equal to about 99%, less than or equal to about95%, less than or equal to about 90%, less than or equal to about 80%,less than or equal to about 70%, less than or equal to about 60%, lessthan or equal to about 50%, less than or equal to about 40%, less thanor equal to about 30%, less than or equal to about 20%, less than orequal to about 15%, less than or equal to about 10%, less than or equalto about 5%, less than or equal to about 3%, or less than or equal toabout 1%. Combinations of the above-referenced ranges are also possible.In some embodiments, the average porosity may range from about 50% toabout 99%, about 70% to about 99%, or from about 80% to about 98%. Thepore size and total porosity values can be quantified using conventionalmethods and models known to those of skill in the art. For example, thepore size and porosity can be measured by standardized techniques, suchas mercury porosimetry and nitrogen adsorption.

In some embodiments, the porous particles (e.g., silk fibroin particles)may have a porosity such that the average density of the particles whenin dried form (e.g., dried and non-compressed silk fibroin particles) isat least about 0.05 g/mL particles, at least about 0.1 g/mL particles,at least about 0.15 g/mL particles, at least about 0.2 g/mL particles,at least about 0.25 g/mL particles, at least about 0.3 g/mL particles,at least about 0.35 g/mL particles, at least about 0.4 g/mL particles,at least about 0.45 g/mL particles, at least about 0.5 g/mL particles,at least about 0.55 g/mL particles, at least about 0.6 g/mL particles,at least about 0.65 g/mL particles, at least about 0.7 g/mL particles,at least about 0.75 g/mL particles, at least about 0.8 g/mL particles,at least about 0.85 g/mL particles, at least about 0.9 g/mL particles,at least about 0.9 g/mL particles, or at least about 1.0 g/mL particles.In some embodiments, the porous particles (e.g., silk fibroin particles)may have a porosity such that the average density of the particles whenin dried form (e.g., dried and non-compressed silk fibroin particles) isno more than 1.0 g/mL particles, no more than 0.95 g/mL particles, nomore than 0.9 g/mL particles, no more than 0.85 g/mL particles, no morethan 0.8 g/mL particles, no more than 0.75 g/mL particles, no more than0.7 g/mL particles, no more than 0.65 g/mL particles, no more than 0.6g/mL particles, no more than 0.55 g/mL particles, no more than 0.5 g/mLparticles, no more than 0.45 g/mL particles, no more than 0.4 g/mLparticles, no more than 0.35 g/mL particles, no more than 0.3 g/mLparticles, no more than 0.25 g/mL particles, or no more than 0.2 g/mLparticles. Combinations of the above-referenced ranges are alsopossible. In some embodiments, the porous particles (e.g., silk fibroinparticles) may have a porosity such that the average density of theparticles when in dried form (e.g., dried and non-compressed silkfibroin particles) is about 0.05 g/mL particles to about 1.0 g/mLparticles, or about 0.1 g/mL particles to about 1 g/mL particles, orabout 0.2 g/mL particles to about 1.0 g/mL particles, or about 0.4 g/mLparticles to about 0.8 g/mL particles, or about 0.5 g/mL particles toabout 0.7 g/mL particles, or about 0.1 g/mL particles to about 0.3 g/mLparticles, or about 0.08 g/mL particles to about 0.15 g/mL particles, orabout 0.1 g/mL particles to about 0.12 g/mL particles.

In some embodiments, the porous particles (e.g., silk fibroin particles)may be hydrated (e.g., in an aqueous solution, including, e.g., but notlimited to water, saline, and/or a buffered solution such as a phosphatebuffered solution) such that the average density of the hydratedparticles (e.g., hydrated and non-compressed silk fibroin particles) isat least about 0.4 g/mL particles, at least about 0.5 g/mL particles, atleast about 0.6 g/mL particles, at least about 0.7 g/mL particles, atleast about 0.8 g/mL particles, at least about 0.9 g/mL particles, or atleast about 1 g/mL particles. In some embodiments, the porous particles(e.g., silk fibroin particles) may be hydrated such that the averagedensity of the hydrated particles (e.g., hydrated and non-compressedsilk fibroin particles) is no more than 1.5 g/mL particles, no more than1.4 g/mL particles, no more than 1.3 g/mL particles, no more than 1.2g/mL particles, no more than 1.1 g/mL particles, no more than 1 g/mLparticles, no more than 0.9 g/mL particles, no more than 0.8 g/mLparticles, no more than 0.7 g/mL particles, no more than 0.6 g/mLparticles, or no more than 0.5 g/mL particles. Combinations of theabove-referenced ranges are also possible. In some embodiments, theporous particles (e.g., silk fibroin particles) may be hydrated suchthat the average density of the hydrated particles (e.g., hydrated andnon-compressed silk fibroin particles) is about 0.4 g/mL particles toabout 1.2 g/mL particles, or about 0.5 g/mL particles to about 1 g/mLparticles, or about 0.6 g/mL particles to about 0.8 g/mL particles, orabout 0.65 g/mL particles to about 0.75 g/mL particles.

The pores of the particles can be of any suitable shape, e.g., circular,elliptical, or polygonal. The porous particles (e.g., silk fibroinparticles) can have an average pore size of less than or equal to about100 μm, less than or equal to about 95 μm, less than or equal to about90 μm, less than or equal to about 85 μm, less than or equal to about 80μm, less than or equal to about 75 μm, less than or equal to about 70μm, less than or equal to about 65 μm, less than or equal to about 60μm, less than or equal to about 55 μm, less than or equal to about 50μm, less than or equal to about 45 μm, less than or equal to about 40μm, less than or equal to about 35 μm, less than or equal to about 30μm, less than or equal to about 25 μm, less than or equal to about 20μm, less than about 15 μm, less than about 10 μm, less than about 5 μm,or less than about 1 μm. In some embodiments, the porous particles(e.g., silk fibroin particles) may have an average pore size of at leastabout 0.1 μm, at least about 0.5 μm, at least about 1 μm, at least about5 μm, at least about 10 μm, at least about 15 μm, at least about 20 μm,at least about 25 μm, at least about 30 μm, at least about 35 μm, atleast about 40 μm at least about 45 μm at least about 50 μm at leastabout 55 μm at least about 60 μm at least about 65 μm at least about 70μm at least about 75 μm at least about 80 μm at least about 85 μm atleast about 90 μm at least about 95 μm or at least about 100 μm.Combinations of the above-referenced ranges are also possible. In someembodiments, the porous particles (e.g., silk fibroin particles) mayhave an average pore size of about 0.1 μm to about 100 or about 15 μm toabout 100 μm or about 20 μm to about 100 μm about 30 μm to about 80 μmor about 30 μm to about 60 μm or about 0.1 μm to about 10 or about 25 μmto about 55 μm or about 30 μm to about 50 μm. In some embodiments, theporous particles (e.g., silk fibroin particles) can comprise pores thatare too small to be detected by methods known in the art. The term “poresize” as used herein refers to a dimension of a pore. In someembodiments, the pore size can refer to the longest dimension of a pore,e.g., a diameter of a pore having a circular cross section, or thelength of the longest cross-sectional chord that can be constructedacross a pore having a non-circular cross-section. In other embodiments,the pore size can refer to the shortest dimension of a pore. As usedherein, the term “average pore size” refers to an average or mean valueof a size distribution of pores of a population of particles (e.g., silkfibroin particles) based on measurements of a selected dimension of apore (e.g., the longest dimension of a pore such as diameter, or acharacteristic length of a pore such as circle equivalent diameter).

In some embodiments, the average pore size can refer to an averagecircle equivalent diameter. A “circle equivalent diameter”(also known as“area equivalent diameter”) is the diameter of a circular pore thatgives the same cross-section area as an equivalent pore (e.g., anequivalent non-circular pore) present in a test sample. Thecross-section area of a pore in a test sample can be determined, e.g.,by SEM analysis of cross-sections of a porous scaffold to determine thecross-section area (A_(pore)) of pores and then determine the circleequivalent diameter (D_(circular)) using the equation:D_(circular)=(4A_(pore)/π)^(1/2).

In some embodiments involving the particles (e.g., silk fibroinparticles) described herein, at least about 40% (including, e.g., atleast about 50%, at least about 60%, at least about 70%, at least about80%, at least about 90% or more and up to 100%) of the pores have anaspect ratio of about 1.0 to about 3.

In some embodiments involving the particles (e.g., silk fibroinparticles) described herein, no more than about 10% (including, e.g., nomore than about 9%, no more than about 8%, no more than about 7%, nomore than about 6%, no more than about 5%, or lower) of the pores havean aspect ratio of at least about 2.5 or higher (e.g., including, e.g.,at least about 3.0, at least about 3.5, at least about 4.0, or higher).

In some embodiments involving the particles (e.g., silk fibroinparticles) described herein, the pores of the particles (e.g., silkfibroin particles) have an average aspect ratio of at least about 1.5,at least about 1.6, at least about 1.7, at least about 1.8, at leastabout 1.9, at least about 2.0. In some embodiments, the pores of theparticles (e.g., silk fibroin particles) have an average aspect ratio ofno more than about 2.5, no more than about 2.4, no more than about 2.3,no more than about 2.2, no more than about 2.1, no more than about 2.0,no more than about 1.9, no more than about 1.8, no more than about 1.7,no more than about 1.6, or lower. Combinations of the above-referencedranges are possible. For example, in some embodiments, the pores of theparticles (e.g., silk fibroin particles) have any average aspect ratioof about 1.5 to about 2.5, or about 1.8 to about 2.0.

In some embodiments involving the particles (e.g., silk fibroinparticles) described above and herein, the pores of the particles (e.g.,silk fibroin particles) have an average circularity of about 0.4 toabout 1.0, or about 0.5 to about 0.9, or about 0.6 to about 0.8.

The porosity (including, e.g., pore shape and/or pore size) of theparticles can be controlled during synthesis and/preparation ofparticles. See, e.g., the compositions and/or methods of making silkfibroin particles as described in International Patent Application filedOct. 31, 2017, by Brown, J. et al., entitled “Compositions ComprisingLow Molecular Weight Silk Fibroin Fragments and Plasticizers,” thecontent of which is incorporated herein by reference.

The particles (e.g., silk fibroin particles) can be in any suitableformat, e.g., dry particles, hydrated particles, lyophilized particles(e.g., particles that have been subject to lyophilization), gelparticles, or viscous liquid particles. In some embodiments of any oneof the compositions described herein, the particles (e.g., silk fibroinparticles) are in the form of lyophilized, spongy particles which arehydrated in their final, packaged form. Such particles may be soft,compressible, and have a low density which may be suitable for mimickingsoft tissue mechanics and allowing tissue ingrowth.

In some embodiments, the particles (e.g., silk fibroin particles) arenot transparent to light, or only allow minimal transmission of light.For example, the particles (e.g., silk fibroin particles) may permitlight (e.g., visible light, e.g., with a wavelength of about 390 nm toabout 700 nm) transmission of at least about 5%, at least about 10%, atleast about 15%, at least about 20%, at least about 30%, at least about40%, at least about 50%, or higher. In some embodiments, the particles(e.g., silk fibroin particles) may permit light (e.g., visible light,e.g., with a wavelength of about 390 nm to about 700 nm) transmission ofless than or equal to about 50%, less than or equal to about 40%, lessthan or equal to 30%, less than or equal to 25%, less than or equal to20%, less than or equal to 15%, less than or equal to 10%, or lower. Insome embodiments, the particles (e.g., silk fibroin particles) canpermit light (e.g., visible light, e.g., with a wavelength of about 390nm to about 700 nm) transmission of about 5% to about 30%, about 7% toabout 30%, or about 10% to 20%. For example, in some embodiments, theoptical transparency of 600 nm light in silk fibroin particles alone(1-2 particle layer thick) is about 7.0% or higher.

Silk Fibroin Particles that Exhibit Little or Minimal PlasticDeformation

Another aspect described herein relates to a novel porous silk fibroinparticle that exhibits little or minimal plastic deformation and itspores exhibit more rounded morphology. For example, the silk fibroinparticle has an average particle size of about 50 μm to about 1000 μmand a porous structure characterized in that:

no more than about 10% of pores within the porous structure have anaspect ratio of about 4.0 or higher; and

when a population of the silk fibroin particles is exposed to acompressive strain of at least about 20%, the silk fibroin particlesrecover at least about 90% of their original volume after release of thecompression.

As used herein, the phrase “silk fibroin particles” generally refers toparticles comprising silk fibroin. In some embodiments, the phrase “silkfibroin particles” refers to particles in which silk fibroin constitutesat least about 30% of the total particle composition, including at leastabout 40%, at least about 50%, at least about 60%, at least about 70%,at least about 80%, at least about 90%, at least about 95% or up to100%, of the total particle composition. In certain embodiments, thesilk fibroin particles can be substantially formed from silk fibroin. Inone embodiment, the silk fibroin particles consist essentially of silkfibroin.

In some embodiments, the silk fibroin particles are substantiallydepleted of its native sericin content (e.g., about 5% (w/w) or lessresidual sericin in the final extracted silk). Alternatively, higherconcentrations of residual sericin can be left on the silk followingextraction or the extraction step can be omitted. In some embodiments,the silk fibroin particles have, e.g., about 0.1% (w/w) residual sericin(or more), about 1% (w/w) residual sericin (or more), about 2% (w/w)residual sericin (or more), about 3% (w/w) residual sericin (or more),about 4% (w/w) (or more), or about 5% (w/w) residual sericin (or more).In some embodiments, the silk fibroin particles have, e.g., at most 1%(w/w) residual sericin, at most 2% (w/w) residual sericin, at most 3%(w/w) residual sericin, at most 4% (w/w), or at most 5% (w/w) residualsericin. Combinations of the above-referenced ranges are also possible.In some other embodiments, the silk fibroin particles have, e.g., about1% (w/w) to about 2% (w/w) residual sericin, about 1% (w/w) to about 3%(w/w) residual sericin, about 1% (w/w) to about 4% (w/w), or about 1%(w/w) to about 5% (w/w) residual sericin. In some embodiments, the silkfibroin particles are entirely free of its native sericin content. Asused herein, the term “entirely free” means that within the detectionrange of the instrument or process being used, the substance cannot bedetected or its presence cannot be confirmed. In some embodiments, thesilk fibroin is essentially free of its native sericin content. As usedherein, the term “essentially free” means that only trace amounts of thesubstance can be detected, is present in an amount that is belowdetection, or is absent.

Silk fibroin is a particularly appealing biopolymer candidate to be usedfor various embodiments described herein, e.g., because of its versatileprocessing, e.g., all-aqueous processing (Sofia et al., 54 J. Biomed.Mater. Res. 139 (2001); Perry et al., 20 Adv. Mater. 3070-72 (2008)),relatively easy functionalization (Murphy et al., 29 Biomat. 2829-38(2008)), and biocompatibility (Santin et al., 46 J. Biomed. Mater. Res.382-9 (1999)). For example, silk has been approved by U.S. Food and DrugAdministration as a tissue engineering scaffold in human implants. SeeAltman et al., 24 Biomaterials: 401 (2003).

As used herein, the term “silk fibroin” includes silkworm fibroin andinsect or spider silk protein. See e.g., Lucas et al., 13 Adv. ProteinChem. 107 (1958). Any type of silk fibroin can be used in differentembodiments described herein. Silk fibroin produced by silkworms, suchas Bornbyx rnori, is the most common and represents an earth-friendly,renewable resource. For instance, silk fibroin may be attained byextracting sericin from the cocoons of Bornbyx rnori. Silkworm cocoonsare commercially available. There are many different silks, however,including spider silk (e.g., obtained from Nephila clavipes), transgenicsilks, genetically engineered silks, such as silks from bacteria, yeast,mammalian cells, transgenic animals, or transgenic plants (see, e.g., WO97/08315; U.S. Pat. No. 5,245,012), and variants thereof, that can beused.

In any one of the embodiments described herein, silk fibroin can bemodified for desired mechanical or chemical properties. One of skill inthe art can select appropriate methods to modify silk fibroins, e.g.,depending on the side groups of the silk fibroins, desired reactivity ofthe silk fibroin and/or desired charge density on the silk fibroin. Inone embodiment, modification of silk fibroin can use the amino acid sidechain chemistry, such as chemical modifications through covalentbonding, or modifications through charge-charge interactions. Exemplarychemical modification methods include, but are not limited to,carbodiimide coupling reaction (see, e.g. U.S. Patent Application. No.US 2007/0212730), diazonium coupling reaction (see, e.g., U.S. PatentApplication No. US 2009/0232963), avidin-biotin interaction (see, e.g.,International Application No.: WO 2011/011347) and pegylation with achemically active or activated derivatives of the PEG polymer (see,e.g., International Application No. WO 2010/057142). Silk fibroin canalso be modified through gene modification to alter functionalities ofthe silk protein (see, e.g., International Application No. WO2011/006133). For instance, the silk fibroin can be geneticallymodified, which can provide for further modification of the silk such asthe inclusion of a fusion polypeptide comprising a fibrous proteindomain and a mineralization domain, which can be used to form anorganic—inorganic composite. See WO 2006/076711.

In some embodiments, silk fibroin can be chemically modified to enhancehydrophilicity (or hydrophobicity), making it more or less hydrophilicin the presence of media. Hydrophilic silk fibroin particles are morelikely to take up aqueous media and swell after injection into a tissueto be treated compared to silk fibroin particles that are lesshydrophilic.

While silk fibroin particles can be of any shape, e.g., a sphericalshape, polygonal-shaped, elliptical-shaped, in some embodiments, thesilk fibroin particles are substantially spherical. A substantiallyspherical particle may have an aspect ratio of (a ratio of the majoraxis to the minor axis) of less than or equal to about 1.5, e.g., about0.5 to about 1.5, about 0.6 to about 1.4, about 0.7 to about 1.3, about0.8 to about 1.2, about 0.9 to about 1.1, or about 1.0 to about 1.1,while a non-spherical particle (e.g., an elongated particle) may have anaspect ratio of more than about 1.5 or higher (e.g., more than about 2,more than about 3, more than about 4, more than about 5 or higher).

In some embodiments involving the silk fibroin particles of this aspectdescribed herein, the average particle size of the silk fibroinparticles is at least about 50 μm, at least about 100 μm, at least about150 μm, at least about 200 μm, at least about 250 μm, at least about 300μm, at least about 350 μm, at least about 400 μm, at least about 450 μm,at least about 500 μm, at least about 550 μm, at least about 600 μm, atleast about 650 μm, at least about 700 μm, at least about 750 μm, atleast about 800 μm, at least about 850 μm, at least about 900 μm, atleast about 950 μm, or at least about 1000 μm. In some embodiments, theaverage particle size of the silk fibroin particles is less than orequal to about 1000 μm, less than or equal to about 950 μm, less than orequal to about 900 μm, less than or equal to about 850 μm, less than orequal to about 800 μm, less than or equal to about 750 μm, less than orequal to about 700 μm, less than or equal to about 650 μm, less than orequal to about 600 μm, less than or equal to about 550 μm, less than orequal to about 500 μm, less than or equal to about 450 μm, less than orequal to about 400 μm, less than or equal to about 350 μm, less than orequal to about 300 μm, less than or equal to about 250 μm, less than orequal to about 200 μm, less than or equal to about 150 μm, less than orequal to about 100 μm, or less than or equal to about 50 μm.Combinations of the above-referenced ranges are also possible. In someembodiments, the average particle size of the silk fibroin particles maybe about 50 μm to about 1000 μm. In some embodiments, the averageparticle size of the silk fibroin particles can be about 250 μm to about850 μm. In some embodiments, the average particle size of the silkfibroin particles can be about 300 μm to about 800 μm. In someembodiments, the average particle size of the silk fibroin particles canbe about 400 μm to about 600 μm. In some embodiments, the averageparticle size of the silk fibroin particles can be about 250 μm to about450 μm. In some embodiments, the average particle size of the silkfibroin particles can be about 200 μm to about 500 μm. In someembodiments, the average particle size of the silk fibroin particles canbe about 300 μm to about 450 μm. In some embodiments of any averageparticle size ranges described herein, the average particle size of silkfibroin particles may refer to volume mean diameter of silk fibroinparticles.

The silk fibroin particles of this aspect have pores and/or cervicesthat are accessible to cells, media, and/or solutes. The pores can be atthe surface of the silk fibroin particles and/or within the bulkstructure of the silk fibroin particles. In some embodiments, the poroussilk fibroin particles may have an average porosity of at least about50%, at least about 55%, at least about 60%, at least about 65%, atleast about 70%, at least about 75%, at least about 80%, at least about85%, at least about 90%, at least about 93%, at least about 95%, atleast about 97%, or higher. In some embodiments, the porous silk fibroinparticles may have an average porosity of less than or equal to about99%, less than or equal to about 98%, less than or equal to about 95%,less than or equal to about 90%, less than or equal to about 85%, lessthan or equal to about 80%, less than or equal to about 75%, less thanor equal to about 70%, less than or equal to about 65%, less than orequal to about 60%, less than or equal to about 55%, or less than orequal to about 50%. Combinations of the above-referenced ranges are alsopossible. In some embodiments, the average porosity may range from about50% to about 99%, about 70% to about 99%, or from about 80% to about98%.

In some embodiments, the porous silk fibroin particles have a porositysuch that the average density of the dried silk fibroin particles (silkfibroin particles in dried and non-compressed form) is at least about0.05 g/mL particles, at least about 0.1 g/mL particles, at least about0.15 g/mL particles, at least about 0.2 g/mL particles, at least about0.25 g/mL particles, at least about 0.3 g/mL particles, at least about0.35 g/mL particles, at least about 0.4 g/mL particles, at least about0.45 g/mL particles, at least about 0.5 g/mL particles, at least about0.55 g/mL particles, at least about 0.6 g/mL particles, at least about0.65 g/mL particles, at least about 0.7 g/mL particles, at least about0.75 g/mL particles, at least about 0.8 g/mL particles, at least about0.85 g/mL particles, at least about 0.9 g/mL particles, at least about0.9 g/mL particles, or at least about 1.0 g/mL particles. In someembodiments, the porous silk fibroin particles may have a porosity suchthat the average density of the dried silk fibroin particles (silkfibroin particles in dried and non-compressed form) is no more than 1.0g/mL particles, no more than 0.95 g/mL particles, no more than 0.9 g/mLparticles, no more than 0.85 g/mL particles, no more than 0.8 g/mLparticles, no more than 0.75 g/mL particles, no more than 0.7 g/mLparticles, no more than 0.65 g/mL particles, no more than 0.6 g/mLparticles, no more than 0.55 g/mL particles, no more than 0.5 g/mLparticles, no more than 0.45 g/mL particles, no more than 0.4 g/mLparticles, no more than 0.35 g/mL particles, no more than 0.3 g/mLparticles, no more than 0.25 g/mL particles, no more than 0.2 g/mLparticles, no more than 0.15 g/mL particles, no more than 0.1 g/mLparticles, or no more than 0.05 g/mL particles. Combinations of theabove-referenced ranges are also possible. In some embodiments, theporous silk fibroin particles may have a porosity such that the averagedensity of the dried silk fibroin particles (silk fibroin particles indried and non-compressed form) is about 0.05 g/mL particles to about 1.0g/mL particles, or about 0.1 g/mL particles to about 1 g/mL particles,or about 0.2 g/mL particles to about 1.0 g/mL particles, or about 0.4g/mL particles to about 0.8 g/mL particles, or about 0.5 g/mL particlesto about 0.7 g/mL particles, or about 0.1 g/mL particles to about 0.3g/mL particles, or about 0.08 g/mL particles to about 0.15 g/mLparticles. In one embodiment, the porous silk fibroin particles may havea porosity such that the average density of the dried and non-compressedsilk fibroin particles is about 0.1 g/mL particles. In one embodiment,the porous silk fibroin particles may have a porosity such that theaverage density of the dried and non-compressed silk fibroin particlesis about 0.1 g/mL particles to about 0.12 g/mL particles.

In some embodiments, the porous particles (e.g., silk fibroin particles)may be hydrated such that the average density of the hydrated particles(e.g., hydrated and non-compressed silk fibroin particles) is at leastabout 0.4 g/mL particles, at least about 0.5 g/mL particles, at leastabout 0.6 g/mL particles, at least about 0.7 g/mL particles, at leastabout 0.8 g/mL particles, at least about 0.9 g/mL particles, or at leastabout 1 g/mL particles. In some embodiments, the porous particles (e.g.,silk fibroin particles) may be hydrated such that the average density ofthe hydrated particles (e.g., hydrated and non-compressed silk fibroinparticles) is no more than 1.5 g/mL particles, no more than 1.4 g/mLparticles, no more than 1.3 g/mL particles, no more than 1.2 g/mLparticles, no more than 1.1 g/mL particles, no more than 1 g/mLparticles, no more than 0.9 g/mL particles, no more than 0.8 g/mLparticles, no more than 0.7 g/mL particles, no more than 0.6 g/mLparticles, or no more than 0.5 g/mL particles. Combinations of theabove-referenced ranges are also possible. In some embodiments, theporous particles (e.g., silk fibroin particles) may be hydrated suchthat the average density of the hydrated particles (e.g., hydrated andnon-compressed silk fibroin particles) is about 0.4 g/mL particles toabout 1.2 g/mL particles, or about 0.5 g/mL particles to about 1 g/mLparticles, or about 0.6 g/mL particles to about 0.8 g/mL particles, orabout 0.65 g/mL particles to about 0.75 g/mL particles.

In some embodiments involving the silk fibroin particles describedherein, at least about 40% (including, e.g., at least about 50%, atleast about 60%, at least about 70%, at least about 80%, at least about90% or more and up to 100%) of the pores have an aspect ratio of about1.0 to about 2.5.

In some embodiments involving the silk fibroin particles describedherein, no more than about 10% (including, e.g., no more than about 9%,no more than about 8%, no more than about 7%, no more than about 6%, nomore than about 5%, or lower) of the pores have an aspect ratio of atleast about 2.5 or higher (e.g., including, e.g., at least about 3.0, atleast about 3.5, at least about 4.0, or higher).

In some embodiments involving the silk fibroin particles describedherein, the pores have an average aspect ratio of at least about 1.5, atleast about 1.6, at least about 1.7, at least about 1.8, at least about1.9, at least about 2.0. In some embodiments, the pores have an averageaspect ratio of no more than about 2.5, no more than about 2.4, no morethan about 2.3, no more than about 2.2, no more than about 2.1, no morethan about 2.0, no more than about 1.9, no more than about 1.8, no morethan about 1.7, no more than about 1.6, or lower. Combinations of theabove-referenced ranges are possible. For example, in some embodiments,the pores have any average aspect ratio of about 1.5 to about 2.5, orabout 1.8 to about 2.0.

In some embodiments involving the silk fibroin particle describedherein, the pores of the silk fibroin particle have an averagecircularity of about 0.4 to about 1.0, or about 0.5 to about 0.9, orabout 0.6 to about 0.8.

In some embodiments, no more than 10% pores within the porous silkfibroin particle have an aspect ratio of about 4.0 or higher. Forexample, in some embodiments, no more than about 10% pores, no more thanabout 9% pores, no more than about 8% pores, no more than about 7%pores, no more than about 6% pores, no more than about 5% pores, no morethan about 4% pores, no more than about 3% pores, no more than about 2%pores, or no more than about 1% pores, within the porous silk fibroinparticle have an aspect ratio of about 4.0, about 4.5, about 5.0, about5.5, about 6.0, or higher. In some embodiments, the porous silk fibroinparticles are substantially free of pores that have an aspect ratio ofabout 4.0, about 4.5, about 5.0, about 5.5, about 6.0, or higher.

In some embodiments of this aspect described herein, at least about 40%of the pores, including, e.g., at least about 50%, at least about 60%,at least about 70%, at least about 80%, at least about 90%, or at leastabout 95% or higher (e.g., up to 100%), of the pores, have an aspectratio of about 1.0 to about 2.0 (inclusive). In these embodiments, atleast about 20% or about 30% of the pores may have an aspect ratio ofabout 1.0 to about 1.5 (inclusive).

As used herein with respect to a pore, the term “aspect ratio” refers toa ratio of the longest dimension of a pore to the shortest dimension ofthe pore. Rounded pores (e.g., pores having a round cross-section)generally have an aspect ratio of about 1.0 to about 1.5. Perfectlyround cross-section has an aspect ratio of about 1.0. Example 6 providesan exemplary method to determine aspect ratios of pores present in asilk fibroin material. For example, in some embodiments where the silkfibroin particles are produced from a bulk silk fibroin sponge, SEManalysis of a cross-section of the bulk silk fibroin sponge (prior toreducing it to particles) can be performed. The contrast of the SEMimages of the cross-section composite can be manipulated using anyart-recognized image analysis tool (e.g., ImageJ or Phenom Porometricsoftware) such that pores of the bulk silk fibroin sponge aredistinguishable from the silk fibroin bulk material. Using an imageanalysis tool, the pores are then outlined, for example, using ellipsesfitting, and the longest and shortest dimensions of the pores aremeasured to determine an aspect ratio of a pore. The aspect ratios of arepresentative number of the pores (e.g., at least 100 or more) aremeasured to create a distribution graph showing percentages of poreswith respect to aspect ratios, for example, as shown in FIGS. 13C and13F. Alternatively, the silk fibroin particles can be embedded in asubstrate material (e.g., a hydrogel) to form a silk fibroin/substratecomposite and then an SEM analysis of a cross-section of the compositecan be performed.

In some embodiments of any one of the silk fibroin particles describedherein, the porous structure of the silk fibroin particles ischaracterized by interconnected pores having an average pore size ofless than or equal to about 100 μm, less than or equal to about 95 μm,less than or equal to about 90 μm, less than or equal to about 85 μm,less than or equal to about 80 μm, less than or equal to about 75 μm,less than or equal to about 70 μm, less than or equal to about 65 μm,less than or equal to about 60 μm, less than or equal to about 55 μm,less than or equal to about 50 μm, less than or equal to about 45 μm,less than or equal to about 40 μm, less than or equal to about 35 μm,less than or equal to about 30 μm, less than or equal to about 25 μm,less than or equal to about 20 μm, less than or equal to about 15 μm,less than or equal to about 10 μm, less than or equal to about 5 μm,less than or equal to about 1 μm, or less than or equal to about 0.5 μm.In some embodiments, the porous silk fibroin particles may have anaverage pore size of at least about 0.1 μm, at least about 0.5 μm, atleast about 1 μm, at least about 5 μm, at least about 10 μm, at leastabout 15 μm, at least about 20 μm, at least about 25 μm, at least about30 μm, at least about 35 μm, at least about 40 μm, at least about 45 μm,at least about 50 μm, at least about 55 μm, at least about 60 μm, atleast about 65 μm, at least about 70 μm, at least about 75 μm, at leastabout 80 μm, at least about 85 μm, at least about 90 μm, at least about95 μm, or at least about 100 μm. Combinations of the above-referencedranges are also possible. For example, in some embodiments, the porousstructure of the silk fibroin particles may be characterized byinterconnected pores having an average pore size of about 0.1 μm toabout 100 μm, or about 0.1 μm to about 10 μm, or about 15 μm to about100 μm, or about 20 μm to about 100 μm, about 30 μm to about 80 μm, orabout 30 μm to about 60 μm, or about 25 μm to about 55 μm, or about 30μm to about 50 μm. In some embodiments, the pores of the silk fibroinparticles may be too small to be detected by methods known in the art.

In some embodiments involving the porous silk fibroin particlesdescribed herein, the porous structure may be characterized by no morethan 10% (including, e.g., no more than about 9%, no more than about 8%,no more than about 7%, no more than about 6%, no more than about 5% orlower) of interconnected pores having a circle equivalent diameter ofabout 100 μm or greater.

In some embodiments involving the porous silk fibroin particlesdescribed herein, the porous structure may be characterized by no morethan 15% (including, e.g., no more than about 14%, no more than about13%, no more than 12%, no more than 11%, no more than 10%, no more thanabout 9%, no more than about 8%, no more than about 7%, no more thanabout 6%, no more than about 5% or lower) of interconnected pores havinga circle equivalent diameter of about 75 μm or greater.

In some embodiments involving the porous silk fibroin particlesdescribed herein, the porous structure may be characterized by at leastabout 50% (including, e.g., at least about 60%, at least about 70%, atleast about 80%, at least about 90%, or above) of interconnected poreshaving a circle equivalent diameter of about 5 μm to about 75 μm, orabout 15 μm to about 60 μm, or about 15 μm to about 55 μm.

In some embodiments of any one of the silk fibroin particles describedherein, the population of the silk fibroin particles exhibit an elasticmodulus (as measured at about 6-10% strain) of at least about 1 kPa, atleast about 2 kPa, at least about 3 kPa, at least about 4 kPa, at leastabout 5 kPa, at least about 10 kPa, at least about 20 kPa, at leastabout 30 kPa, at least about 40 kPa, at least about 50 kPa, at leastabout 60 kPa, at least about 70 kPa, at least about 80 kPa, at leastabout 90 kPa, or at least about 100 kPa. In some embodiments of any oneof the silk fibroin particles described herein, the population of thesilk fibroin particles exhibit an elastic modulus (as measured at about6-10% strain) of less than or equal to about 100 kPa, less than or equalto about 90 kPa, less than or equal to about 80 kPa, less than or equalto about 70 kPa, less than or equal to about 60 kPa, less than or equalto about 50 kPa, less than or equal to about 40 kPa, less than or equalto about 30 kPa, less than or equal to about 20 kPa, less than or equalto about 10 kPa, or less than or equal to about 5 kPa. Combinations ofthe above-referenced ranges are also possible. For example, in someembodiments, the population of the silk fibroin particles exhibit about1 kPa to about 100 kPa, about 1 kPa to about 50 kPa, about 1 kPa toabout 30 kPa, about 1 kPa to about 20 kPa, or about 5 kPa to about 20kPa, or about 40 kPa to about 100 kPa, about 50 kPa to about 90 kPa, orabout 60 kPa to about 80 kPa (as measured at about 6% axial strain). Theelastic modulus can be measured using the method as described in Example8.

When a population of the silk fibroin particles of this aspect describedherein is exposed to a compressive strain of at least about 10% (e.g.,including, e.g., at least about 20%, at least about 25%, at least about30%, at least about 35%, at least about 40%, at least about 45%, atleast about 50%, at least about 55%, at least about 60%, at least about65%, at least about 70%, at least about 75%, at least about 80%, atleast about 85%, at least about 90% or higher), the silk fibroinparticles recover at least about 50%, at least about 55%, at least about60%, at least about 65%, at least about 70%, at least about 75%, atleast about 80%, at least about 85%, at least about 90%, at least about95%, at least about 98%, at least about 99%, or up to 100%, of theiroriginal volume (e.g., hydrated state such as fully saturated withwater) after release of the compression. In some embodiments, the silkfibroin particles recover no more than 100%, no more than 95%, no morethan 90%, no more than 85%, no more than 80%, no more than 75%, no morethan 70%, no more than 65%, no more than 60%, no more than 55%, no morethan 50%, no more than 45%, or more than 40%, of their original volume(e.g., hydrated state such as fully saturated with water) after releaseof the compression. Combinations of the above-referenced ranges are alsopossible. For example, in some embodiments, when a population of thesilk fibroin particles is exposed to a compressive strain of at leastabout 10% (e.g., including, e.g., at least about 20%, at least about30%, at least about 40%, at least about 50%, at least about 60%, atleast about 70%, at least about 80%, at least about 90% or higher), thesilk fibroin particles recover about 40%-100%, about 50-100%, about60-99%, about 70-99%, about 80-99%, or about 90-100%, or about 90-99% oftheir original volume (e.g., hydrated state such as fully saturated withwater) after release of the compression. The compression recovery of thematerial can be measured using the method as described in Example 8.

The mechanics (e.g., elastic modulus and/or compression recovery) ofindividual silk fibroin particles can also be determined by atomic forcemicroscope or other microscopic methods.

In some embodiments, the silk fibroin particles that exhibit compressionrecovery and/or elastic modulus as described above and herein comprise aplasticizer, for example, in the amount of about 0.001% (w/w) to about30% (w/w), about 0.01% (w/w) to about 30% (w/w), about 0.1% (w/w) toabout 30% (w/w), or about 1% (w/w) to about 30% (w/w). In someembodiments, the silk fibroin particles that exhibit compressionrecovery and/or elastic modulus as described above and herein comprise aplasticizer, for example, in the amount of about 0.001% (w/w) to about20% (w/w), about 0.01% (w/w) to about 20% (w/w), about 0.1% (w/w) toabout 20% (w/w), or about 1% (w/w) to about 20% (w/w). In someembodiments, the silk fibroin particles that exhibit compressionrecovery and/or elastic modulus as described above and herein comprise aplasticizer, for example, in the amount of about 0.001% (w/w) to about10% (w/w), about 0.01% (w/w) to about 10% (w/w), about 0.1% (w/w) toabout 10% (w/w), or about 1% (w/w) to about 10% (w/w). Examples of aplasticizer include, but are not limited to alcohols containing at leastone hydroxyl group (including, e.g., methanol; ethanol; propanolisomers, e.g., 1-propanol, isopropyl alcohol; butanol isomers, e.g.,n-butanol, sec-butanol, isobutanol, tert-butanol; pentanol isomers (amylalcohol), e.g., n-pentanol, isobutyl carbinol, active amyl alcohol,tertiary butyl carbinol, 3-pentanol, methyl (n) propyl carbinol, methylisopropyl carbinol, dimethyl ethyl carbinol; hexanol, e.g., n-hexanoland related isomers; heptanol and related isomers; octanol and relatedisomers; nonanol and related isomers; and decanol and related isomers);sugars or simple sugars (including, e.g., sucrose, glucose; fructose;ribose; galactose; maltose; lactose; triose; tetrose; pentose; hexose;trehalose; and any other monosaccharides, disaccharides,oligosaccharides, and polysaccharides); polyols containing multiplehydroxyl groups (including, e.g., diols; vicinal diols (hydroxyl groupsattached to adjacent atoms: examples include but are not limited to:propane-1,2-diol; ethylene glycol; propylene glycol); 1,3 diols (e.g.,propane-1,3-diol; 2,2-dimethyl-1,3-propanediol; 1,3 butanediol; 1,4diols (e.g., 1,4-butanediol, 1,4-pentanediol); 1,5 diols and longer;triols (e.g., Glycerol, Benzenetriol, Pyrogallol, 1,2,6 Hexanetriol,1,3,5-pentanetriol; Phenols (e.g., hydroquinone, resorcinol,meta-cresol, eugenol, thymol, pyrogallol); sugar alcohols or polyhydricalcohols; arabitol; erythritol; fucitol; galactitol; iditol; inositol;isomalt; lactitol; maltitol; maltotetraitol; maltotriitol; mannitol;ribitol (adonitol); sorbitol; threitol; volemitol; xylitol; and anycombinations thereof. In one set of embodiments of the silk fibroinparticles of this aspect, the plasticizer is glycerol, for example, inthe amount of about 1% (w/w) to about 10% (w/w). See, e.g., WO2010/042798, Modified Silk Films Containing Glycerol.

The silk fibroin particles described herein can exist in differentstates, e.g., in hydrated state or dried state. In some embodimentsinvolving the silk fibroin particle described above and herein, the silkfibroin particles are lyophilized silk fibroin particles.

Compositions or Injectable Compositions Comprising the Silk FibroinParticles Described Herein

Also provided herein are compositions comprising one or more silkfibroin particles as described above and herein and a carrier (which maycomprise a single carrier or a mixture of two or more carriers (e.g., afirst carrier and a second carrier of the same or different weightaverage molecular weights). In some embodiments, the carrier is not amixture of two HA components of different weight average molecularweights. The silk fibroin particles and the carrier can be present inany volume ratio that yields properties of the compositions suitable forthe need of a particular application. In some embodiments of any one ofthe compositions or injectable compositions described herein, the silkfibroin particles and the carrier (e.g., total amount of carrier) arepresent in a volume ratio of at least about 5:95, at least about 10:90,at least about 15:85, at least about 20:80, at least about 25:75, atleast about 30:70, at least about 35:65, at least about 40:60, at leastabout 45:55, at least about 50:50, at least about 55:45, at least about60:40, at least about 65:35, at least about 70:30, at least about 75:25,at least about 80:20, at least about 85:15, at least about 90:10, or atleast about 95:5. In some embodiments, the silk fibroin particles andthe carrier (e.g., total amount of carrier) are present in a volumeratio of less than or equal to about 100:1, less than or equal to about95:5, less than or equal to about 90:10, less than or equal to about85:15, less than or equal to about 80:20, less than or equal to about75:25, less than or equal to about 70:30, less than or equal to about65:35, less than or equal to about 60:40, less than or equal to about55:45, less than or equal to about 50:50, less than or equal to about45:55, less than or equal to about 40:60, less than or equal to about35:65, less than or equal to about 30:70, less than or equal to about25:75, less than or equal to about 20:80, less than or equal to about15:85, less than or equal to about 10:90, or less than or equal to about5:95. Combinations of the above-referenced ranges are also possible. Forexample, in some embodiments of any one of the compositions orinjectable compositions described herein, the silk fibroin particles andthe carrier (e.g., total amount of carrier) are present in a volumeratio of about 5:95 to about 95:5, or about 10:90 to about 90:10, orabout 20:80 to about 80:20, or about 25:75 to about 75:25, or about30:70 to about 70:30, or about 40:60 to about 60:40. In someembodiments, the silk fibroin particles and the carrier are present in avolume ratio of about 50:50; about 40:60; about 30:70; about 25:75;about 20:80, or about 10:90, or as low as about 5:95. In someembodiments, the silk fibroin particles and the carrier are present in avolume ratio of about 60:40, about 70:30, about 75:25; about 80:20,about 90:10 or up to about 95:5.

One or more mechanical properties of any one of the compositions orinjectable compositions described herein can be tuned to substantiallymatch (e.g., within about 30% or less, within about 20% or less, withinabout 15% or less, within about 10% or less, within about 9% or less,within about 8% or less, within about 7% or less, within about 6% orless, within about 5% or less, within about 4% or less, within about 3%or less, within about 2% or less, within about 1% or less, or lower) thecorresponding mechanical property of a soft tissue to which thecompositions are injected. By way of example only, the stiffness of anyone of the compositions or injectable compositions described herein canbe tuned to substantially match (e.g., within about 30% or less, withinabout 20% or less, within about 15% or less, within about 10% or less,within about 9% or less, within about 8% or less, within about 7% orless, within about 6% or less, within about 5% or less, within about 4%or less, within about 3% or less, within about 2% or less, within about1% or less, or lower) the stiff tissue of a soft tissue to which thecompositions are injected.

In some embodiments, the compositions described herein exhibit shearthinning behavior with increasing frequency.

In some embodiments of any one of the compositions or injectablecompositions described herein, the composition has a stiffness that ischaracterized by shear storage modulus (G′) of a soft tissue to betreated, e.g., within the range of 0.1-10 kPa. In some embodiments ofany one of the compositions or injectable compositions described herein,the composition has a stiffness that is characterized by shear storagemodulus (G′) of human vocal fold tissue, e.g., within the range of0.01-1 kPa for the frequency range of 1-100 Hz (10 rad/s=1.59 Hz). See,e.g., Miri, A., “Mechanical Characterization of Vocal Fold Tissue: AReview Study,” 2014, Journal of Voice. In some embodiments of any one ofthe compositions or injectable compositions described herein, thecomposition has a stiffness that is characterized by shear storagemodulus (G′) of at least about 100 Pa, at least about 150 Pa, at leastabout 200 Pa, at least about 250 Pa, at least about 300 Pa, at leastabout 350 Pa, at least about 400 Pa, at least about 450 Pa, at leastabout 500 Pa, at least about 550 Pa, at least about 600 Pa, at leastabout 650 Pa, at least about 700 Pa, at least about 750 Pa, at leastabout 800 Pa, at least about 850 Pa, at least about 900 Pa, at leastabout 950 Pa, at least about 1000 Pa, at least about 1050 Pa, at leastabout 1100 Pa, at least about 1150 Pa, at least about 1200 Pa, at leastabout 1250 Pa, at least about 1300 Pa, at least about 1350 Pa, at leastabout 1400 Pa, at least about 1450 Pa, at least about 1500 Pa, at leastabout 2000 Pa, at least about 3000 Pa, at least about 4000 Pa, or atleast about 5000 Pa. In some embodiments, the composition has astiffness that is characterized by G′ of less than or equal to about5,000 Pa, less than or equal to about 4,000 Pa, less than or equal toabout 2,000 Pa, less than or equal to about 1500 Pa, less than or equalto about 1450 Pa, less than or equal to about 1400 Pa, less than orequal to about 1350 Pa, less than or equal to about 1300 Pa, less thanor equal to about 1250 Pa, less than or equal to about 1200 Pa, lessthan or equal to about 1150 Pa, less than or equal to about 1100 Pa,less than or equal to about 1050 Pa, less than or equal to about 1000Pa, less than or equal to about 950 Pa, less than or equal to about 900Pa, less than or equal to about 850 Pa, less than or equal to about 800Pa, less than or equal to about 750 Pa, less than or equal to about 700Pa, less than or equal to about 650 Pa, less than or equal to about 600Pa, less than or equal to about 550 Pa, less than or equal to about 500Pa, less than or equal to about 450 Pa, less than or equal to about 400Pa, less than or equal to about 350 Pa, less than or equal to about 300Pa, less than or equal to about 250 Pa, less than or equal to about 200Pa, less than or equal to about 150 Pa, or less than or equal to about100 Pa. Combinations of the above-referenced ranges are also possible.For example, in some embodiments of any one of the compositions orinjectable compositions provided herein, the composition has a stiffnessthat is characterized by shear storage modulus (G′) of about 100 Pa toabout 1500 Pa, or about 150 Pa to about 1250 Pa, or about 200 Pa toabout 1000 Pa, or about 250 Pa to about 950 Pa, or about 300 Pa to about900 Pa. In some embodiments, the composition can have a shear storagemodulus (G′) of about 400 Pa to about 1000 Pa, or about 500 Pa to about900 Pa. In some embodiments, the composition can have a shear storagemodulus (G′) of about 100 Pa to about 500 Pa or about 100 Pa to about400 Pa. In some embodiments, the shear storage modulus provided hereincorrespond to the value obtained at an angular frequency (or a shearfrequency) of about 1Hz. Without wishing to be bound by theory, theshear storage modulus may gradually increase with increasing frequency.For example, for silk fibroin particles suspended in a crosslinkedhyaluronic acid (HA) carrier, the storage modulus of the suspension isabout 1 kPa measured at a frequency of about 0.1 Hz and up to about 6kPa measured at a frequency of about 10 Hz.

In some embodiments of any one of the compositions or injectablecompositions described herein, the composition is characterized by shearloss modulus (G″) of a soft tissue to be treated, e.g., within the rangeof 0.01-1 kPa. In some embodiments of any one of the compositions orinjectable compositions described herein, the composition ischaracterized by shear loss modulus (G″) of human vocal fold tissue,e.g., within the range of 0.05-0.7 kPa for the frequency range of 1-100Hz. See, e.g., Miri, A., “Mechanical Characterization of Vocal FoldTissue: A Review Study,” 2014, Journal of Voice. In some embodiments ofany one of the compositions or injectable compositions described herein,the composition is characterized by shear loss modulus (G″) of at leastabout 25 Pa, at least about 50 Pa, at least about 75 Pa, at least about100 Pa, at least about 150 Pa, at least about 200 Pa, at least about 250Pa, at least about 300 Pa, at least about 350 Pa, at least about 400 Pa,at least about 450 Pa, at least about 500 Pa, at least about 550 Pa, atleast about 600 Pa, at least about 650 Pa, at least about 700 Pa, atleast about 750 Pa, at least about 800 Pa, at least about 850 Pa, atleast about 900 Pa, at least about 950 Pa, at least about 1000 Pa, atleast about 1050 Pa, at least about 1100 Pa, at least about 1150 Pa, atleast about 1200 Pa, at least about 1250 Pa, at least about 1300 Pa, atleast about 1350 Pa, at least about 1400 Pa, at least about 1450 Pa, orat least about 1500 Pa. In some embodiments, the composition ischaracterized by G″ of less than or equal to about 1500 Pa, less than orequal to about 1450 Pa, less than or equal to about 1400 Pa, less thanor equal to about 1350 Pa, less than or equal to about 1300 Pa, lessthan or equal to about 1250 Pa, less than or equal to about 1200 Pa,less than or equal to about 1150 Pa, less than or equal to about 1100Pa, less than or equal to about 1050 Pa, less than or equal to about1000 Pa, less than or equal to about 950 Pa, less than or equal to about900 Pa, less than or equal to about 850 Pa, less than or equal to about800 Pa, less than or equal to about 750 Pa, less than or equal to about700 Pa, less than or equal to about 650 Pa, less than or equal to about600 Pa, less than or equal to about 550 Pa, less than or equal to about500 Pa, less than or equal to about 450 Pa, less than or equal to about400 Pa, less than or equal to about 350 Pa, less than or equal to about300 Pa, less than or equal to about 250 Pa, less than or equal to about200 Pa, less than or equal to about 150 Pa, less than or equal to about100 Pa, less than or equal to about 75 Pa, less than or equal to about50 Pa, or less than or equal to about 25 Pa. Combinations of theabove-referenced ranges are also possible. For example, in someembodiments of any one of the compositions or injectable compositionsprovided herein, the composition is characterized by shear loss modulus(G″) of about 25 Pa to about 1500 Pa, or about 50 Pa to about 1250 Pa,or about 100 Pa to about 1000 Pa, or about 150 Pa to about 950 Pa, orabout 200 Pa to about 900 Pa. In some embodiments, the shear lossmodulus provided herein correspond to the value obtained at an angularfrequency (or a shear frequency) of about 1Hz. Both shear storage andshear loss moduli can be measured simultaneously using the same testingset-up, e.g., a parallel plate set-up. Similar to shear storage modulus,shear loss modulus can slightly increase with increasing frequencies.

An exemplary method of assessing certain mechanical properties (e.g.,the shear storage modulus and shear loss modulus) of the compositionsdescribed herein (e.g., a suspension of silk fibroin particles in acarrier described herein) is shear rheometry with parallel plate set-upat a temperature of 25° C. For example, test protocols for oscillatorystrain sweeps, frequency sweeps and steady state shear measurements canbe adapted from Malvern Instruments Application Notes: “Evaluating therheological properties of hyaluronic acid hydrogels for dermal fillerapplications,” 2015; and Stocks et al., “Rheological Evaluation of thephysical properties of hyaluronic acid dermal fillers,” 2011, Journal ofDrugs in Dermatology, the contents of each of which are incorporatedherein by reference in their entireties. See Example 10 for exemplarymethods for determination of such mechanical property measurements.

In some embodiments of any one of the compositions or injectablecompositions described herein, the composition is characterized bycomplex shear modulus (G*) of a soft tissue to be treated, e.g., withinthe range of 0.1-10 kPa. In some embodiments of any one of thecompositions or injectable compositions described herein, thecomposition is characterized by complex shear modulus (G*) of humanvocal fold tissue, e.g., within the range of 0.01-1 kPa for thefrequency range of 1-100 Hz. In some embodiments of any one of thecompositions or injectable compositions described herein, thecomposition is characterized by complex shear modulus (G*) of humanvocal fold tissue, e.g., within the range of 1-10 kPa for the frequencyrange of 0.1-10 Hz. In some embodiments of any one of the compositionsor injectable compositions described herein, the composition ischaracterized by complex shear modulus (G*) of at least about 100 Pa, atleast about 150 Pa, at least about 200 Pa, at least about 250 Pa, atleast about 300 Pa, at least about 350 Pa, at least about 400 Pa, atleast about 450 Pa, at least about 500 Pa, at least about 550 Pa, atleast about 600 Pa, at least about 650 Pa, at least about 700 Pa, atleast about 750 Pa, at least about 800 Pa, at least about 850 Pa, atleast about 900 Pa, at least about 950 Pa, at least about 1000 Pa, atleast about 1050 Pa, at least about 1100 Pa, at least about 1150 Pa, atleast about 1200 Pa, at least about 1250 Pa, at least about 1300 Pa, atleast about 1350 Pa, at least about 1400 Pa, at least about 1450 Pa, orat least about 1500 Pa, at least about 2000 Pa, at least about 3000 Pa,at least about 4000 Pa, at least about 5000 Pa, at least about 6000 Pa,or at least about 7000 Pa. In some embodiments, the composition ischaracterized by G* of less than or equal to about 7000 Pa, less than orequal to about 6,000 Pa, less than or equal to about 5,000 Pa, less thanor equal to about 4,000 Pa, less than or equal to about 2,000 Pa, lessthan or equal to about 1500 Pa, less than or equal to about 1450 Pa,less than or equal to about 1400 Pa, less than or equal to about 1350Pa, less than or equal to about 1300 Pa, less than or equal to about1250 Pa, less than or equal to about 1200 Pa, less than or equal toabout 1150 Pa, less than or equal to about 1100 Pa, less than or equalto about 1050 Pa, less than or equal to about 1000 Pa, less than orequal to about 950 Pa, less than or equal to about 900 Pa, less than orequal to about 850 Pa, less than or equal to about 800 Pa, less than orequal to about 750 Pa, less than or equal to about 700 Pa, less than orequal to about 650 Pa, less than or equal to about 600 Pa, less than orequal to about 550 Pa, less than or equal to about 500 Pa, less than orequal to about 450 Pa, less than or equal to about 400 Pa, less than orequal to about 350 Pa, less than or equal to about 300 Pa, less than orequal to about 250 Pa, less than or equal to about 200 Pa, less than orequal to about 150 Pa, or less than or equal to about 100 Pa.Combinations of the above-referenced ranges are also possible. Forexample, in some embodiments of any one of the compositions orinjectable compositions provided herein, the composition may becharacterized by complex shear modulus (G*) of about 100 Pa to about1500 Pa, or about 150 Pa to about 1250 Pa, or about 200 Pa to about 1000Pa, or about 250 Pa to about 950 Pa, or about 300 Pa to about 900 Pa. Insome embodiments, the composition may have a complex shear modulus (G*)of about 400 Pa to about 1000 Pa, or about 500 Pa to about 900 Pa. Insome embodiments, the composition may have a complex shear modulus (G*)of about 100 Pa to about 500 Pa or about 100 Pa to about 400 Pa. In someembodiments, the complex shear modulus provided herein correspond to thevalue obtained at an angular frequency (or a shear frequency) of about0.1-10 Hz (e.g., 1Hz). In some embodiments, the composition may have acomplex shear modulus (G*) of about 1 kPa to about 10 kPa, or about 2kPa to about 8 kPa, or about 2 kPa to about 7 kPa measured within afrequency range of about 0.1 Hz to 10 Hz. Without wishing to be bound bytheory, the complex shear modulus may gradually increase with increasingfrequency. G* is a derived value from the measured G′ and G″. Therefore,G* can be computed from the equation G*=G′+iG“. In some embodiments, theranges and trends of G* mimic closely the values and ranges of the shearstorage modulus, G′, e.g., when G” is an order of magnitude less thanG′, so the value of G* is primarily dictated by G′.

In some embodiments, the compositions described herein are elasticacross a frequency of 0.1-10 Hz (e.g., the value of G′ is greater thanthe value G″ for all frequencies between 0.1-10 Hz by at least 10-fold,at least 20-fold, at least 30-fold, at least 40-fold, at least 50-fold,at least 100-fold, or higher). Furthermore, it is contemplated that atfrequencies lower than the range presented (<0.1 Hz), the compositionsdescribed herein would continue to exhibit elastic behavior. Only atvery high frequencies, e.g., well above 100 Hz, and well outside thephysiologically relevant range that the compositions would experience inthe body, the compositions may begin to yield and may exhibit asignificant reduction in elastic behavior.

In some embodiments of any one of the compositions described herein, thecomposition is characterized by elasticity of at least about 50% ormore, including, e.g., at least about 55%, at least about 60%, at leastabout 65%, at least about 70%, at least about 75%, at least about 80%,at least about 85%, at least about 90%, at least about 95%, or more. Insome embodiments, the composition is characterized by an elasticity ofless than or equal to about 99%, less than or equal to about 95%, lessthan or equal to about 90%, less than or equal to about 85%, less thanor equal to about 80%, less than or equal to about 75%, less than orequal to about 70%, or less than or equal to about 60%. Combinations ofthe above-referenced ranges are also possible, In some embodiments, thecomposition is characterized by elasticity of about 50% to about 95%, orabout 60% to about 90% or about 70% to about 85%. In some embodiments,the composition exhibits such elasticity at a shear frequency of atleast 5 rad/s or higher, e.g., at least about 10 rad/s, at least about20 rad/s, at least about 25 rad/s, at least about 50 rad/s, at leastabout 75 rad/s, or at least about 100 rad/s. In some embodiments, thecompositions described herein are elastic across a frequency of 0.1-10Hz (e.g., the value of G′ is greater than the value G″ for allfrequencies between 0.1-10 Hz by at least 10-fold, at least 20-fold, atleast 30-fold, at least 40-fold, at least 50-fold, at least 100-fold, orhigher). Furthermore, it is contemplated that at frequencies lower thanthe range presented (<0.1 Hz), the compositions described herein wouldcontinue to exhibit elastic behavior. Only at very high frequencies,e.g., well above 100 Hz, and well outside the physiologically relevantrange that the compositions would experience in the body, thecompositions may begin to yield and may exhibit a significant reductionin elastic behavior.

As used herein, the term “elasticity” or “elastic” describes the elasticproperty of a material or composition, e.g., the ability of a materialor composition to deform reversibly under applied stress, or to recoverits pre-stressed shape and/or volume after removal of the appliedstress. In some embodiments, the values of elasticity provided hereincan be determined by rheometry at an angular frequency (or shearfrequency) of 10 rad/s and computed as follows:Elasticity=100%×G′/(G′+G″),where G′ is the shear storage modulus; and G″ is the shear loss modulus.In one set of embodiments, the values of elasticity provided herein canbe determined by rheometry at an angular frequency of 10 rad/s.

The carrier may be selected from the examples of carriers discussed inthe section “Carriers” below or otherwise as described herein. In someembodiments, the carrier may comprise glycosaminoglycan polymers (e.g.,crosslinked or non-crosslinked hyaluronic acid, keratan sulfate,chondroitin sulfate, and/or heparin), extracellular matrix proteinpolymers (e.g., collagen, elastin, and/or fibronectin), polysaccharides(e.g., cellulose), fibrous protein polymers, a fat material (e.g.,derived from a lipoaspirate), and a combination of two or more thereof.

In some embodiments of any compositions and/or injectable compositionsdescribed herein, the carrier may have a concentration of at least about0.1% (w/v), at least about 0.5% (w/v), at least about 1% (w/v), at leastabout 2% (w/v), at least about 3% (w/v), at least about 4% (w/v), atleast about 5% (w/v), at least about 6% (w/v), at least about 7% (w/v),at least about 8% (w/v), at least about 9% (w/v), or at least about 10%(w/v). In some embodiments, the carrier may have a concentration of lessthan or equal to about 10% (w/v), less than or equal to about 9% (w/v),less than or equal to about 8% (w/v), less than or equal to about 7%(w/v), less than or equal to about 6% (w/v), less than or equal to about5% (w/v), less than or equal to about 4% (w/v), less than or equal toabout 3% (w/v), less than or equal to about 2% (w/v), less than or equalto about 1% (w/v), less than or equal to about 0.5% (w/v), or less thanor equal to about 0.1% (w/v). Combinations of the above-referencedranges are also possible. For example, in some embodiments, the carriermay have a concentration of about 0.1% (w/v) to about 10% (w/v), about1% (w/v) to about 10% (w/v), about 1% (w/v) to about 8% (w/v), about 1%(w/v) to about 6% (w/v), or about 1% (w/v) to about 5% (w/v). In someembodiments, the hyaluronic acid polymer may have a concentration ofabout 1% (w/v), about 2% (w/v), about 3% (w/v), about 4% (w/v), about 5%(w/v), about 6% (w/v), about 7% (w/v), about 8% (w/v), about 9% (w/v),or about 10% (w/v).

In some embodiments of any compositions and/or injectable compositionsdescribed herein where the carrier is a single carrier, the carrier ishyaluronic acid (e.g., crosslinked hyaluronic acid). In theseembodiments, the density of hydrated (e.g., fully saturated with water)silk fibroin particles/hyaluronic acid composition is at least about 0.5g/mL composition, at least about 0.55 g/mL composition, at least about0.6 g/mL composition, at least about 0.65 g/mL composition, at leastabout 0.7 g/mL composition, at least about 0.75 g/mL composition, atleast about 0.8 g/mL composition, at least about 0.85 g/mL composition,at least about 0.9 g/mL composition, at least about 0.95 g/mLcomposition, at least about 1.0 g/mL composition, at least 1.1 g/mLcomposition, at least 1.2 g/mL composition, at least 1.3 g/mLcomposition, at least 1.4 g/mL composition, or at least 1.5 g/mLcomposition. In some embodiments, the density of hydrated (e.g., fullysaturated with water) silk fibroin particles/hyaluronic acid compositionis no more than 1.5 g/mL composition, no more than 1.4 g/mL composition,no more than 1.3 g/mL composition, no more than 1.2 g/mL composition, nomore than 1.1 g/mL, no more than 1.0 g/mL composition, no more than 0.95g/mL composition, no more than 0.9 g/mL composition, no more than 0.85g/mL composition, no more than 0.8 g/mL composition, no more than 0.75g/mL composition, no more than 0.7 g/mL composition, no more than 0.65g/mL composition, no more than 0.6 g/mL composition, no more than 0.55g/mL composition, or no more than 0.5 g/mL composition. Combinations ofthe above-referenced ranges are also possible. In some embodiments, thedensity of hydrated (e.g., fully saturated with water) silk fibroinparticles/hyaluronic acid composition is about 0.5 g/mL composition toabout 1.5 g/mL composition, or about 0.7 g/mL composition to about 1.3g/mL composition, or about 0.8 g/mL composition to about 1.2 g/mLcomposition, or about 1.0 g/mL composition to about 1.2 g/mLcomposition, or about 1.1 g/mL composition.

In some embodiments, the density of hydrated (e.g., fully saturated withan aqueous solution, including, e.g., but not limited to water, saline,and/or a buffered solution such as a phosphate buffered solution) silkfibroin particles/hyaluronic acid composition being about 1.1 g/mLcomposition corresponds to a composition in which hyaluronic acid has aweight average molecular weight of about 800 kDa to about 900 kDa (e.g.,about 823 kDa to about 884 kDa) and the crosslinked HA has a crosslinkdensity of about 4 mol % to about 15 mol % (e.g., about 13 mol %).

In some embodiments of any compositions and/or injectable compositionsdescribed herein, the carrier may comprise two or more carriers (e.g., afirst carrier and a second carrier). Thus, in these embodiments, thecomposition comprises silk fibroin particles, a first carrier, and asecond carrier. The first carrier and the second carrier can eachindependently be selected from the examples of carriers discussed in thesection “Carriers” below or otherwise as described herein. In someembodiments, the first carrier and the second carrier can eachindependently comprise glycosaminoglycan polymers (e.g., crosslinked ornon-crosslinked hyaluronic acid, keratan sulfate, chondroitin sulfate,and/or heparin), extracellular matrix protein polymers (e.g., collagen,elastin, and/or fibronectin), polysaccharides (e.g., cellulose), fibrousprotein polymers, a fat material (e.g., derived from a lipoaspirate),and a combination of two or more thereof. In one set of embodiments, atleast one or both of the first carrier and the second carrier is/are ahyaluronic acid polymer (crosslinked and/or non-crosslinked).

In some embodiments, the carrier (e.g., the first carrier and optionallythe second carrier), e.g., for soft tissue filling applications, can beindependently a material that satisfies one or more (e.g., 1, 2, 3, 4)of the following conditions:

-   -   a highly viscous material with a predominantly elastic behavior        (via oscillatory rheology);        -   These two features are generally applicable for properly            suspending particles. Low viscosity materials generally            cause particles to settle over time, which can affect            performance and storage.    -   biocompatibility, minimal to no cytotoxicity;    -   tunable mechanical features (either by controlling molecular        weight, crosslinking, and/or concentration of particles and/or        carriers, or other parameters); and    -   biodegradability, which is mediated by the surrounding        tissues/cells, or can be triggered by addition of a specific        protease or enzyme (e.g. hyaluronidase).        There may be additional criteria involving other types of        mechanical features which may be used for selecting first and/or        second carriers in other embodiments.

In some embodiments where there are more than one types of carriers in acomposition, the first carrier and the second carrier may have differentaverage molecular weights. In some embodiments where the first carrieris HA, the second carrier is not HA of a different average molecularweight. Using at least two carriers of different average molecularweights may provide flexibility to control injectability and/ordegradation tunability of the composition. In some embodiments, thesecond carrier may have a higher average molecular weight than that ofthe first carrier. For example, the average molecular weight of thesecond carrier may be higher than that of the first carrier by at leastabout 50% or higher, including, e.g., by at least about 55%, at leastabout 60%, at least about 65%, at least about 70%, at least about 75%,at least about 80%, at least about 85%, at least about 90%, at leastabout 95%, or higher. In some embodiments, the average molecular weightof the second carrier can be higher than that of the first carrier by atleast 1.1-fold or higher, including, e.g., at least 1.5-fold, 2-fold,2.5-fold, 3-fold, 3.5-fold, 4-fold, 4.5-fold, 5-fold, or higher, e.g.,up to 10-fold or less. In some embodiments, the average molecular weightof the second carrier can be higher than that of the first carrier byless than or equal to about 500%, less than or equal to about 450%, lessthan or equal to about 400%, less than or equal to about 350%, less thanor equal to about 300%, less than or equal to about 250%, less than orequal to about 200%, less than or equal to about 150%, less than orequal to about 100%, less than or equal to about 95%, less than or equalto about 90%, less than or equal to about 80%, less than or equal toabout 70%, less than or equal to about 60%, or less than or equal toabout 50%. Combinations of the above-referenced ranges are alsopossible. The presence of more than one carriers (e.g., two or more, orthree or more) of different average molecular weights may result in thecarrier having a multimodal (e.g., a bimodal) molecular weightdistribution. The average molecular weights provided herein and belowfor the first carrier and second carrier can correspond to weightaverage molecular weights, number average molecular weights, or peakaverage molecular weights. The average molecular weights provided hereinand below for the first carrier and second carrier can be determined byany known methods in the art, including, e.g., but not limited to, gelelectrophoresis (e.g., sodium dodecyl sulfate polyacrylamide gelelectrophoresis (SDS-PAGE), size exclusion gel chromatography, massspectroscopy (e.g., MALDI or ESI), or high performance liquidchromatography (HPLC), refractive index detection, light scattering, orany combinations thereof.

In one set of the embodiments described herein, the average molecularweights provided herein and below for the first carrier and secondcarrier correspond to weight average molecular weights, for example, asdetermined by size exclusion chromatography.

The volume ratio of the first carrier to the second carrier can varyaccording to the need of an application, e.g., to achieve a particularextrusion force and/or degradation rate. In some embodiments of any oneof the compositions or injectable compositions described herein wherethere are more than one types of carriers, the volume ratio of the firstcarrier to the second carrier is at least about 5:95; at least about10:90, at least about 15:85, at least about 20:80, at least about 25:75,at least about 30:70, at least about 35:65, at least about 40:60, atleast about 45:55, at least about 50:50, at least about 55:45, at leastabout 60:40, at least about 65:35, at least about 70:30, at least about75:25, at least about 80:20, at least about 85:15, at least about 90:10,or at least about 95:5. In some embodiments, the volume ratio of thefirst carrier to the second carrier is less than or equal to about90:10, less than or equal to about 85:15, less than or equal to about80:20, less than or equal to about 75:25, less than or equal to about70:30, less than or equal to about 65:35, less than or equal to about60:40, less than or equal to about 55:45, less than or equal to about50:50, less than or equal to 45:55, less than or equal to 40:60, lessthan or equal to 35:65, less than or equal to 30:70, less than or equalto 25:75, less than or equal to 20:80, less than or equal to 15:85, lessthan or equal to 10:90, less than or equal to 5:95. Combinations of theabove-referenced ranges are also possible. In some embodiments, thevolume ratio of the first carrier to the second carrier can be about50:50 to about 90:10, or about 60:40 to 90:10, or about 70:30 to about90:10, or about 80:20 to about 90:10. In some embodiments, the volumeratio of the first carrier to the second carrier can be about 5:95 toabout 50:50, about 5:95 to about 40:60 or about 10:90 to about 30:70.

In some embodiments of any one of the compositions described above orherein, the composition is an injectable composition. As used herein,the term “injectable composition” generally refers to a composition thatcan be delivered or administered into a tissue with a minimally invasiveprocedure. The term “minimally invasive procedure” refers to a procedurethat is carried out by entering a subject's body through the skin orthrough a body cavity or an anatomical opening, but with the smallestdamage possible (e.g., a small incision, injection). In someembodiments, the injectable composition can be administered or deliveredinto a tissue by injection. In some embodiments, the injectablecomposition can be delivered into a tissue through a small incision intoa tissue or skin followed by insertion of a needle, a cannula, and/ortubing, e.g., a catheter.

In some embodiments of any one of the compositions described herein, thecomposition is characterized in that a standard deviation of extrusionforce of the composition through a 18-30 (e.g., 18, 19, 20, 21, 22, 23,24, 25, 26, 27, 28, 29, or 30) gauge needle into air, as determinedbetween about 50% extrusion volume and about 90% extrusion volume, isless than about 40%, less than about 35%, less than about 30%, less thanabout 25%, less than about 20%, less than about 15%, less than about10%, less than about 5%, or less than about 1%, of an average extrusionforce for the corresponding range of the extrusion volume (i.e., about50%-about 90% extrusion volume). In some embodiments, the standarddeviation of extrusion force of the composition through a 18-30 (e.g.,18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30) gauge needle intoair, as determined between about 50% extrusion volume and about 90%extrusion volume, is at least about 0.1%, at least about 0.5%, at leastabout 1%, at least about 5%, at least about 10%, at least about 15%, orat least about 20%, of an average extrusion force for the correspondingrange of the extrusion volume (i.e., about 50%-about 90% extrusionvolume). Combinations of the above-referenced ranges are also possible.For example, in some embodiments, the standard deviation of extrusionforce of the composition through a 18-30 (e.g., 18, 19, 20, 21, 22, 23,24, 25, 26, 27, 28, 29, or 30) gauge needle into air, as determinedbetween about 50% extrusion volume and about 90% extrusion volume, isabout 0.1% to about 40%, or about 1% to about 20%, or about 1% to about15%, of an average extrusion force for the corresponding range of theextrusion volume (i.e., about 50%-about 90% extrusion volume).

In some embodiments of any compositions or injectable compositionsdescribed herein, the stiffness of the composition is decreased by atleast about 10%, at least about 15%, at least about 20%, at least about30%, at least about 40%, at least about 50%, at least about 60%, atleast about 70%, at least about 80%, at least about 90%, or higher, asmeasured between about 0.1% strain and about 1% strain, or between about0.1% strain and about 10% strain, or between about 1% strain and about100% strain, or between about 10% strain and about 90% strain. In someembodiments, the stiffness of the composition is decreased by no morethan about 95%, no more than about 90%, no more than about 80%, no morethan about 70%, no more than about 60%, no more than about 50%, no morethan about 40%, no more than about 30%, or no more than about 20%, asmeasured between about 0.1% strain and about 1% strain, or between about0.1% strain and about 10% strain, or between about 1% strain and about100% strain, or between about 10% strain and about 90% strain.Combinations of the above-referenced ranges are also possible. In someembodiments, the stiffness of the composition is decreased by about 10%to about 90% or about 15% to about 80%, or about 10% to about 40% orabout 10% to about 30%, as measured between about 0.1% strain and about1% strain, or between about 0.1% strain and about 10% strain, or betweenabout 1% strain and about 100% strain, or between about 10% strain andabout 90% strain.

In some embodiments of any one of the compositions described herein, thecomposition is characterized in that an average force of extruding about1 mL of the composition (e.g., using a 1-mL syringe) through a 18-30gauge needle (e.g., 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or30 gauge) into air (e.g., under atmospheric pressure) is less than 60 N,including, for example less than 50 N, less than 40 N, less than 30 N,less than 20 N, less than 15 N, less than 10 N, or less than 5 N. Insome embodiments, the composition is characterized in that an averageforce of extruding about 1 mL of the composition through a 18-30 gaugeneedle (e.g., 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30gauge) into air is equal to or more than 5 N, equal to or more than 10N, equal to or more than 15 N, equal to or more than 20 N, equal to ormore than 30 N, equal to or more than 40 N, equal to more than 50 N,equal to or more than 60 N. Combinations of the above-referenced rangesare also possible. For example, in some embodiments, the composition ischaracterized in that an average force of extruding about 1 mL of thecomposition through a 18-30 gauge needle (e.g., 18, 19, 20, 21, 22, 23,24, 25, 26, 27, 28, 29, or 30 gauge) into air is about 5 N to about 60N, about 10 N to about 50 N, or about 15 N to about 50 N, or about 20 Nto about 50 N, or about 5 N to about 60 N.

In some embodiments where the total amounts of the silk fibroinparticles and the carrier are in a volume ratio of about 5:95 to about95:5 (inclusive), an average force of extruding about 1 mL of thecomposition (e.g., using a 1-mL syringe) through a 18-30 gauge needle(e.g., 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 gauge) intoair (e.g., under atmospheric pressure) is less than 60 N, including, forexample less than 50 N, less than 40 N, less than 30 N, less than 20 N,less than 15 N, less than 10 N, or less than 5 N. In some embodiments,the composition is characterized in that an average force of extrudingabout 1 mL of the composition through a 18-30 gauge needle (e.g., 18,19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 gauge) into air isequal to or more than 5 N, equal to or more than 10 N, equal to or morethan 15 N, equal to or more than 20 N, equal to or more than 30 N, equalto or more than 40 N, equal to more than 50 N, equal to or more than 60N. Combinations of the above-referenced ranges are also possible. Forexample, in some embodiments, the composition is characterized in thatan average force of extruding about 1 mL of the composition through a18-30 gauge needle (e.g., 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28,29, or 30 gauge) into air is about 5 N to about 60 N, about 10 N toabout 50 N, or about 15 N to about 50 N, or about 20 N to about 50 N, orabout 5 N to about 60 N.

In some embodiments where the total amounts of the silk fibroinparticles and the carrier are in a volume ratio of less than or equal toabout 50:50 (e.g., e.g., less than or equal to about 40:60, or less thanor equal to about 30:70, less than or equal to about 20:80, or lower,inclusive), an average force of extruding about 1 mL of the compositiondescribed herein through a 18-25 gauge (e.g., 18, 19, 20, 21, 22, 23,24, or 25 gauge) needle into air (e.g., atmospheric pressure) is about30 N or lower (e.g., about 25 N or lower, about 20 N or lower, about 15N or lower, about 10 N or lower, or about 5 N or lower). Alternatively,an average force of extruding about 1 mL of the composition through a25-30 gauge (e.g., 25G, 26G, 27G, 28G, 29G, or 30G) gauge needle intoair is less than 40N (e.g., about 35 N or lower, about 30 N or lower,about 25 N or lower, about 20 N or lower, about 15 N or lower, about 10N or lower, or about 5 N or lower). In some embodiments, when the totalamounts of the particles and the carrier are in a volume ratio of 40:60or lower (e.g., 30:70), an average force of extruding about 1 mL of thecomposition through a 21 gauge needle into air is about 30 N or lower.

In some embodiments, at least about 80% or higher (including, e.g., atleast about 85%, at least about 90%, at least about 95%, at least about98%, or higher, up to 100%) of the silk fibroin particles in thecompositions described herein are substantially spherical particles(e.g., having an aspect ratio of less than or equal to about 1.5, suchas about 0.9 to about 1.1 or about 1.0 to about 1.1).

In some embodiments, the silk fibroin particles in any one of thecompositions described herein are substantially monodispersed. As usedtherein, the term “substantially monodispersed” refers to a populationof silk fibroin particles having a narrow particle size distribution.For example, the particle size distribution can be characterized byparticle size uniformity as defined below,

${Uniformity} = \frac{\sum{X_{i}{❘{{d\left( {x,0.5} \right)} - {di}}❘}}}{{d\left( {x,0.5} \right)}{\sum X_{i}}}$where d is the mean diameter and X is the frequency/percentage. Thevalues of uniformity range from 0-1 where 0 represents completelymonodisperse populations. In some embodiments, the particle sizeuniformity of the silk fibroin particles is at least about 0, at leastabout 0.1, at least about 0.2, at least about 0.3, at least about 0.4,or at least about 0.5. In some embodiments, the particle size uniformityof the silk fibroin particles is no more than 0.5, no more than 0.4, nomore than 0.3, no more than 0.2, no more than 0.1, or no more than 0.05.Combinations of the above-referenced ranges are also possible. Forexample, in some embodiments, the particle size uniformity of the silkfibroin particles may be about 0-0.4, or about 0-0.5. In someembodiments, the particle size uniformity of the silk fibroin particlesis about 0, about 0.1, about 0.2, about 0.3, or about 0.4 (inclusive).The particle size can be measured by any methods known in the art or asdescribed herein.

The average particle size of the silk fibroin particles in someembodiments involving the compositions described herein may be selectedto suit the need of each application. For example, smaller averageparticle size may be desirable for vocal fold augmentation, while largeraverage particle size may be more suitable for large volumereconstruction (e.g., breast reconstruction). Accordingly, in someembodiments, the silk fibroin particles have an average particle size ofabout 250 μm to about 450 μm, or about 300 μm to about 400 μm. Inalternative embodiments, the silk fibroin particles may have an averageparticle size of about 400 μm to about 600 μm or about 450 μm to about550 μm. In some embodiments, the silk fibroin particles may have anaverage particle size of about 50 μm to about 200 μm. In someembodiments, the silk fibroin may have an average particle size of about75 μm to about 125 μm.

In some embodiments involving the compositions of any aspects describedabove and herein, the compositions may include any suitable inactiveingredient included in U.S. Food & Drug Administration (FDA)'s databasefor Generally Recognized as Safe (GRAS) substances, which is accessibleonline at accessdata.fda.gov/scripts/fdcc/?set=SCOGS.

In some embodiments involving the compositions described above andherein, where the carrier comprises crosslinked hyaluronic acid, thecomposition may comprise residual chemical(s). For example, in someembodiments, about 1 mL dose of the composition comprising silk fibroinparticles (having an average particle size of about 300 microns to 450microns) can possess no more than about 250 micrograms of residuallithium, including, e.g., no more than 200 micrograms, no more thanabout 150 micrograms, no more than about 100 micrograms, no more thanabout 50 micrograms, no more than about 25 micrograms, no more thanabout 10 micrograms, no more than about 5 micrograms, of residuallithium. In some embodiments, about 1 mL dose of the compositioncomprising silk fibroin particles (having an average particle size ofabout 300 microns to 450 microns) can possess no more than about 250micrograms, including, e.g., no more than about 200 micrograms, no morethan about 150 micrograms, no more than about 100 micrograms, no morethan about 50 micrograms, no more than about 25 micrograms, no more thanabout 10 micrograms, no more than about 5 micrograms, of residualbromide. In some embodiments, about 1 mL dose of the compositioncomprising silk fibroin particles (having an average particle size ofabout 300 microns to 450 microns) can possess no more than about 30 mg,including, e.g., no more than about 20 mg, no more than about 10 mg, nomore than about 5 mg, no more than about 1 mg, no more than about 0.5mg, no more than about 0.1 mg, or no more than about 0.01 mg, ofresidual methanol. In some embodiments, the crosslinked hyaluronic acidin the composition can comprise no more than about 2 ppm, including,e.g., no more than about 1 ppm, no more than about 0.5 ppm, no more thanabout 0.1 ppm, or no more than about 0.05 ppm, of residual crosslinkingagent (e.g., 1,4-butanediol diglycidyl ether (BDDE)).

In some embodiments involving the compositions of any aspects describedabove and herein, the injectable composition may be pre-loaded in adelivery device, e.g., a syringe or any embodiment of the deliverydevices described herein.

Delivery Devices

In some embodiments, a delivery device may be used to deliver acomposition to a subject. In some embodiments, the device may be coupledto a laryngoscope or other endoscope.

In some embodiments, the device may include tubing that may include aninner tube and an outer sheath tube. In some embodiments, the device mayinclude a hollow needle that is connected to the inner tube and in fluidcommunication with the inner tube. In some embodiments, the inner tubemay be positioned inside the outer sheath tube. The outer sheath tubemay have an inside diameter that is larger than the outside diameter ofthe inner tube. In some cases, the outer sheath tube may help to preventthe needle from breaking as the device is coupled to an endoscope orlaryngoscope. In some embodiments, a diameter-reduced portion, e.g., ataper, may be formed at the distal end of the outer sheath tube so as toenable control of how far the needle and inner tube may be distallyextended relative to the outer sheath tube.

In some embodiments, the inner tube extends through a channel of ahandle and is connected to and in fluid communication with a syringethat is attached to the handle. As such, a composition may be extrudedfrom the syringe into the inner tube. The inner tube and needle may bemoved through the outer sheath tube by actuating the handle. In someembodiments, the handled is actuated by sliding one portion of thehandle relative to another portion of the handle.

Although the description herein is directed primarily to delivering thecompositions described herein, in some embodiments, the delivery devicedescribed herein may be used to deliver other compositions. The devicemay be used to deliver compositions to the vocal folds, cervix, urinarytract, larynx, pelvis, or other parts of the body in other embodiments.

FIG. 22 depicts an illustrative example of a delivery device 1 fordelivering a composition to a subject according to one set ofembodiments. The device 1 may include a needle 10, tubing 50, and ahandle 100. The needle 10 may be hollow in order to deliver thecomposition through the needle to the patient. In some embodiments, thetubing 50 includes a tube that is connected to the needle such thatmovement of the inner tube also moves the needle. The inner tube mayalso be in fluid communication with the needle such that fluid can enterfrom the inner tube into the needle. In some embodiments, the inner tubemay be referred to as a catheter or a needle catheter. In someembodiments, the tubing 50 may also include an outer sheath tube suchthat the tube connected to the needle may be positioned within the outersheath tube. As such, the tube connected to the needle may also bereferred to as an inner tube.

The needle may be moved through the outer sheath tube of the tubing suchthat the needle may be moved from a retracted position in which theneedle is covered by the outer sheath tube to an extended, deployedposition in which the needle tip is exposed outside of the outer sheathtube in order to pierce tissue and deliver composition to a target site.The outer sheath tube of the tubing may connect to a distal end of thehandle 100, and the inner tube of the tubing may run through a channelwithin the handle. In some embodiments, the inner tube may connect to acontainer, such as a syringe, (not shown in FIG. 22 ) holding thecomposition. The inner tube may be in fluid communication with thesyringe such that the composition may be moved from the syringe into theinner tube, and then into the needle. In some embodiments, the proximalend of the handle may connect to the syringe. In some embodiments, thehandle may include an actuation mechanism that moves the needle from aretracted position to an extended, deployed position.

FIG. 23 depicts an enlarged view of the distal end of the device 1. InFIG. 23 , a portion of the needle 10 may be located within the outersheath tube of the tubing 50. The needle 10 is shown in the extended,deployed position in FIG. 23 , in which the tip of the needle has beenmoved out of the outer sheath tube of tubing 50 and is exposed. In theextended, deployed position, the needle is able to penetrate into aninjection site, such as tissue, in order to deliver composition.

FIG. 24 depicts an enlarged view of the needle 10. The needle 10 mayinclude a needle body 11 and a needle tip 12. In some embodiments, theneedle tip 12 may end in a point 14. As discussed above, the needle maybe hollow. A cross-section of the needle body is shown in FIG. 25 ,which shows the inside diameter D1 and outside diameter D2 of the needlebody 11.

In some embodiments, the needle body may have an inside diameter D1 ofat least about 0.3 mm, at least about 0.4 mm, at least about 0.45 mm, atleast about 0.5 mm, at least about 0.55 mm, at least about 0.6 mm, atleast about 0.7 mm, at least about 0.8 mm or at least about 0.9 mm. Insome embodiments, the needle body may have an inside diameter D1 of lessthan or equal to about 0.9 mm, less than or equal to about 0.8 mm, lessthan or equal to about 0.7 mm, less than or equal to about 0.6 mm, lessthan or equal to about 0.55 mm, less than or equal to about 0.5 mm, lessthan or equal to about 0.45 mm or less than or equal to about 0.4 mm.Combinations of the above-referenced ranges are also possible. Forexample, in some embodiments, the needle body may have an insidediameter D1 of about 0.3 mm to about 0.9 mm, or about 0.4 mm to about0.8 mm, or about 0.45 mm to about 0.55 mm, or about 0.65 mm to about0.75 mm.

In some embodiments, the needle body may have an outside diameter D2 ofat least about 0.4 mm, at least about 0.5 mm, at least about 0.6 mm, atleast about 0.65 mm, at least about 0.7 mm, at least about 0.75 mm, atleast about 0.8 mm, at least about 0.9 mm, or at least about 1.0 mm. Insome embodiments, the needle body may have an outside diameter D2 ofless than or equal to about 1.0 mm, less than or equal to about 0.9 mm,less than or equal to about 0.8 mm, less than or equal to about 0.75 mm,less than or equal to about 0.7 mm, less than or equal to about 0.65 mm,less than or equal to about 0.6 mm, less than or equal to about 0.55 mm,less than or equal to about 0.5 mm, or less than or equal to about 0.4mm. Combinations of the above-referenced ranges are also possible. Forexample, in some embodiments, the needle body may have an outsidediameter D2 of about 0.4 mm to about 0.9 mm, or about 0.5 to about 0.8mm, or about 0.55 to about 0.75 mm, or about 0.6 mm to about 0.7 mm, orabout 0.63 mm to about 0.68 mm, or about 0.6 mm to about 1.0 mm, orabout 0.7 mm to about 0.9 mm, or about 0.75 mm to about 0.85 mm, orabout 0.7 mm.

In some embodiments, the needle body may have a thickness, i.e., thedifference between D1 and D2, of at least about 0.03 mm, at least about0.04 mm, at least about 0.045 mm, at least about 0.05 mm, at least about0.065 mm, at least about 0.07 mm, at least about 0.085 mm, at leastabout 0.1 mm, at least about 0.125 mm, at least about 0.15 mm, at leastabout 0.175 mm, at least about 0.2 mm, at least about 0.25 mm, or atleast about 0.3 mm. In some embodiments, the needle body may have athickness of less than or equal to about 0.3 mm, less than or equal toabout 0.25 mm, less than or equal to about 0.2 mm, less than or equal toabout 0.175 mm, less than or equal to about 0.16 mm, less than or equalto about 0.15 mm, less than or equal to about 0.125 mm, less than orequal to about 0.1 mm, less than or equal to about 0.09 mm, less than orequal to about 0.085, less than or equal to about 0.065 mm, less than orequal to about 0.05 mm, or less than or equal to about 0.045 mm.Combinations of the above-referenced ranges are also possible. Forexample, in some embodiments, the needle body may have a thickness ofabout 0.03 mm to about 0.3 mm, or about 0.04 mm to about 0.1 mm, orabout 0.04 mm to about 0.25 mm, or about 0.4 mm to about 0.2 mm, orabout 0.125 to about 0.175 mm, or about 0.14 mm to about 0.16 mm, orabout 0.045 mm to about 0.085 mm, or about 0.8 mm.

In some embodiments, having a thin needle body thickness may have thebenefit of having a large enough needle inside diameter to allow passageof material such as viscous material, and yet having a small enoughneedle outside diameter to allow the needle to fit within an outersheath tube that is small enough to be endoscopically delivered. In someembodiments, the needle is formed from a hypotube. In some embodiments,the needle may be made of stainless steel or other metal or metal alloy,or other suitable material.

In some embodiments, the needle may have a needle gauge of 18-30 (e.g.,18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30) gauge. In someembodiments, the needle may have a needle gauge of 23XX gauge.

The needle may be movable within the outer sheath tube between a fullyextended state, as shown in FIG. 23 , and a retracted state in which theentire needle is located within the outer sheath tube. In someembodiments, when the hollow needle is in the fully extended state, adistance from a distal end of the hollow needle to a distal end of theouter sheath tube may be at least about 4 mm, at least about 5 mm, atleast about 5.5 mm, at least about 6 mm, or at least about 7 mm. In someembodiments, when the hollow needle is in the fully extended state, adistance from a distal end of the hollow needle to a distal end of theouter sheath tube may be less than or equal to about 10 mm, less than orequal to about 9 mm, less than or equal to about 8.5 mm, less than orequal to about 8 mm, or less than or equal to about 7 mm. Combinationsof the above-referenced ranges are also possible. For example, in someembodiments, when the hollow needle is in the fully extended state, adistance from a distal end of the hollow needle to a distal end of theouter sheath tube may be about 4 mm to about 10 mm, or about 5 mm toabout 9 mm, or about 5.5 mm to about 8.5 mm, or about 6 mm to about 8mm.

In some embodiments, the needle 10 may include a needle tip 12, whichmay end in a point 14. In some embodiments, a frontside triple point cutis used to form the needle tip 12. Detailed views of the needle tipgeometry are shown in the top view of FIG. 26A and the side view of FIG.26B.

In some embodiments, such as that shown in FIG. 26A, the needle tip 12has a tip point angle A1. In some embodiments, the angle A1 may be atleast about 10 degrees, at least about 12 degrees, at least about 14degrees, at least about 14.5 degrees, at least about 15 degrees, atleast about 15.5 degrees, at least about 16 degrees, or at least about18 degrees. In some embodiments, angle A1 may be less than or equal toabout 20 degrees, less than or equal to about 18 degrees, less than orequal to about 17 degrees, less than or equal to about 16 degrees, lessthan or equal to about 15.5 degrees, less than or equal to about 15degrees, less than or equal to about 14.5 degrees, less than or equal toabout 14 degrees, or less than or equal to about 12 degrees.Combinations of the above-referenced ranges are also possible. Forexample, in some embodiments, angle A1 may be about 10 degrees to about20 degrees, or about 12 degrees to about 18 degrees, or about 13 degreesto about 17 degrees, or about 14 degrees to about 16 degrees, or about14.5 degrees to about 15.5 degrees, or about 14.8 degrees to about 15.2degrees.

In some embodiments, such as that shown in FIG. 26B, the needle tip hasa bevel angle A2. In some embodiments, the angle A2 may be at leastabout 10 degrees, at least about 11 degrees, at least about 11.5degrees, at least about 12 degrees, at least about 12.5 degrees, atleast about 13 degrees, at least about 13.5 degrees, at least about 14degrees, at least about 14.5 degrees, or at least about 15 degrees. Insome embodiments, angle A2 may be less than or equal to about 15degrees, less than or equal to about 14.5 degrees, less than or equal toabout 14 degrees, less than or equal to about 13.5 degrees, less than orequal to about 13 degrees, less than or equal to about 12.5 degrees,less than or equal to about 12 degrees, less than or equal to about 11.5degrees, less than or equal to about 11 degrees, or less than or equalto about 10 degrees. Combinations of the above-referenced ranges arealso possible. For example, in some embodiments, angle A1 may be about10 degrees to about 15 degrees, about 12 degrees to about 15 degrees,about 10 degrees to about 14 degrees, about 11 degrees to about 13degrees, about 11.5 degrees to about 12.5 degrees, or about 11.8 degreesto about 12.2 degrees.

In some embodiments, the needle tip geometry may be formed into a tubeof material, e.g., by starting with a tube of material and grinding theneedle tip geometry into the tubing.

In some embodiments, such as that shown in FIG. 26A, the needle has atotal length L1. In some embodiments, the length L1 may be at leastabout 10 mm, at least about 12 mm, at least about 14 mm, at least about15 mm, at least about 15 0.5 mm, at least about 16 mm, at least about 17mm, at least about 18 mm, at least about 20 mm, or at least about 22 mm.In some embodiments, length L1 may be less than or equal to about 30 mm,less than or equal to about 28 mm, less than or equal to about 26 mm,less than or equal to about 24 mm, less than or equal to about 22 mm,less than or equal to about 20 mm, less than or equal to about 18 mm,less than or equal to about 17 mm, less than or equal to about 16.5 mm,less than or equal to about 16 mm, less than or equal to about 15.5 mm,less than or equal to about 15 mm, less than or equal to about 14 mm,less than or equal to about 12 mm, or less than or equal to about 10 mm.Combinations of the above-referenced ranges are also possible. Forexample, in some embodiments, length L1 may be about 10 mm to about 20mm, or about 14 mm to about 18 mm, or about 15 mm to about 17 mm, orabout 15.5 to about 16.5 mm.

According to one aspect, the device tubing may have an angled bend at adistal portion of the tubing. The inventors have recognized thatcreating a bend in the tubing at the distal portion of the tubing mayaid in visualization of the needle during an endoscopic procedure. Oneillustrative embodiment is shown in FIG. 27 , which depicts an enlargedview of a distal portion of the tubing 50. As shown in FIG. 27 , thetubing 50 may have a main body 51 and a distal portion 52. The distalportion 52 may be angled relative to the main body 51 by angle A3 due tobend 53.

In some embodiments, the angle A3 may be at least about 8 degrees, atleast about 10 degrees, at least about 12 degrees, at least about 14degrees, at least about 14.5 degrees, at least about 15 degrees, atleast about 15.5 degrees, at least about 16 degrees, at least about 18degrees, at least about 20 degrees, or at least about 22 degrees. Insome embodiments, angle A3 may be less than or equal to about 20degrees, less than or equal to about 18 degrees, less than or equal toabout 16 degrees, less than or equal to about 15.5 degrees, less than orequal to about 15 degrees, less than or equal to about 14.5 degrees,less than or equal to about 14 degrees, less than or equal to about 12degrees, or less than or equal to about 10 degrees. Combinations of theabove-referenced ranges are also possible. For example, in someembodiments, angle A3 may be about 10 degrees to about 20 degrees, orabout 12 degrees to about 18 degrees, or about 14 degrees to about 16degrees, or about 14.5 degrees to about 15.5 degrees, or about 14.8degrees to about 15.2 degrees.

In some embodiments, the bend 53 may be located at a distance L5 awayfrom the tip of the distal portion 52 of the tubing 50. In someembodiments, the distance L5 may be at least about 10 mm, at least about11 mm, at least about 12 mm, at least about 13 mm, at least about 14 mm,at least about 15 mm, at least about 16 mm, at least about 17 mm, atleast about 18 mm, at least about 19 mm, at least about 20 mm, at leastabout 21 mm, at least about 22 mm, at least about 23 mm, or at leastabout 23 mm. In some embodiments, the distance L5 may be less than orequal to about 24 mm, less than or equal to about 23 mm, less than orequal to about 22 mm, less than or equal to about 21 mm, less than orequal to about 20 mm, less than or equal to about 19 mm, less than orequal to about 18 mm, less than or equal to about 17 mm, less than orequal to about 16 mm, less than or equal to about 15 mm, less than orequal to about 14 mm, less than or equal to about 13 mm, less than orequal to about 12 mm, less than or equal to about 11 mm, or less than orequal to about 10 mm. Combinations of the above-referenced ranges arealso possible. For example, in some embodiments, distance L5 may beabout 10 mm to about 24 mm, or about 11 mm to about 23 mmm, or about 12mm to about 22 mm, or about 13 mm to about 21 mm, or about 14 mm toabout 20 mm, or about 16 mm to about 18 mm.

In some embodiments, as shown in FIG. 23 , with the needle 10 fullyextended, the bend 53 may be located at a distance L6 away from the tipof the needle. In some embodiments, the distance L6 may be at leastabout 15 mm, at least about 18 mm, at least about 20 mm, at least about22 mm, at least about 24 mm, at least about 26 mm, at least about 28 mm,at least about 30 mm, at least about 32 mm, at least about 34 mm, or atleast about 36 mm. In some embodiments, the distance L6 may be less thanor equal to about 36 mm, less than or equal to about 34 mm, less than orequal to about 32 mm, less than or equal to about 30 mm, less than orequal to about 28 mm, less than or equal to about 26 mm, less than orequal to about 24 mm, less than or equal to about 22 mm, less than orequal to about 20 mm, less than or equal to about 18 mm, or less than orequal to about 16 mm. Combinations of the above-referenced ranges arealso possible. For example, in some embodiments, distance L6 may beabout 15 mm to about 36 mm, or about 16 mm to about 34 mm, or about 18mm to about 32 mm, or about 20 mm to about 30 mm, or about 22 mm toabout 28 mm, or about 24 mm to about 26 mm.

As discussed above, in some embodiments, the tubing may comprise aninner tube and an outer sheath tube. In some embodiments, the tubes arepositioned and dimensioned such that the inner tube is able to slidewithin the outer sheath tube. A cross-section of the tubing 50 is shownin FIG. 28 , which depicts an inner tube 60 and an outer sheath tube 70.In some embodiments, the outer sheath tube 70 and/or the inner tube 60may have an angled distal portion relative to a main body of the tube asdescribed above with respect to angle A3.

In some embodiments, the inner tube may have an inside diameter D3 of atleast about 0.7 mm, at least about 0.8 mm, at least about 0.85 mm, atleast about 0.9 mm, at least about 0.95 mm, at least about 1 mm, atleast about 1.05 mm, at least about 1.1 mm, at least about 1.15 mm, orat least about 1.2 mm. In some embodiments, the inner tube may have aninside diameter of less than or equal to about 1.3 mm, less than orequal to about 1.2 mm, less than or equal to about 1.15 mm, less than orequal to about 1.1 mm, less than or equal to about 1.05 mm, less than orequal to about 1 mm, less than or equal to about 0.95 mm, less than orequal to about 0.9 mm, or less than or equal to about 0.8 mm.Combinations of the above-referenced ranges are also possible. Forexample, in some embodiments, the inner tube may have an inside diameterof about 0.7 mm to about 1.2 mm, or about 0.8 mm to about 1.1 mm, orabout 0.85 mm to about 1.15 mm, or about 0.9 mm to about 1.1 mm, orabout 0.95 to about 1.05 mm.

In some embodiments, the inner tube may have an outside diameter of atleast about 1 mm, at least about 1.2 mm, at least about 1.35 mm, atleast about 1.4 mm, at least about 1.45 mm, at least about 1.5 mm, atleast about 1.55 mm, at least about 1.6 mm, or at least about 1.65 mm.In some embodiments, the inner tube may have an outside diameter of lessthan or equal to about 1.8 mm, less than or equal to about 1.7 mm, lessthan or equal to about 1.65 mm, less than or equal to about 1.6 mm, lessthan or equal to about 1.55 mm, less than or equal to about 1.5 mm, lessthan or equal to about 1.45 mm, less than or equal to about 1.4 mm, lessthan or equal to about 1.2 mm, or less than or equal to about 1 mm.Combinations of the above-referenced ranges are also possible. Forexample, in some embodiments, the inner tube may have an outsidediameter of about 1 mm to about 1.8 mm, or about 1.1 mm to about 1.7 mm,or about 1.2 mm to about 1.6 mm, or about 1.3 mm to about 1.5 mm, orabout 1.3 mm to about 1.4 44, or about 1.35 mm to about 1.45 mm, orabout 1.6 mm to about 1.8 mm.

In some embodiments, the outer sheath tube may have an inside diameterof at least about 1.2 mm, at least about 1.3 mm, at least about 1.4 mm,at least about 1.5 mm, at least about 1.55 mm, at least about 1.6 mm, atleast about 1.7 mm, at least about 1.8 mm or at least about 1.9 mm. Insome embodiments, the outer sheath tube may have an inside diameter ofless than or equal to about 1.9 mm, less than or equal to about 1.8 mm,less than or equal to about 1.7 mm, less than equal to about 1.65 mm,less than or equal to about 1.6 mm, less than or equal to about 1.5 mm,less than or equal to about 1.45 mm, or less than or equal to about 1.4mm. Combinations of the above-referenced ranges are also possible. Forexample, in some embodiments, the outer sheath tube may have an insidediameter of about 1.2 mm to about 1.7 mm, or 1.3 mm to about 1.6 mm, orabout 1.4 mm to about 1.5 mm, or about 1.42 mm to about 1.47 mm.

In some embodiments, the outer sheath tube may have an outside diameterD4 of at least about 1.5 mm, at least about 1.6 mm, at least about 1.7mm, at least about 1.75 mm, at least about 1.8 mm, at least about 1.85mm, at least about 1.9 mm, at least about 2 mm, at least about 2.1 mm,or at least about 2.2 mm. In some embodiments, the outer sheath tube mayhave an outside diameter of less than or equal to about 2.2 mm, lessthan or equal to about 2.1 mm, less than or equal to about 2 mm, lessthan or equal to about 1.95 mm, less than or equal to about 1.9 mm, lessthan or equal to about 1.85 mm, less than or equal to about 1.8 mm, lessthan or equal to about 1.7 mm, less than or equal to about 1.6 mm, orless than or equal to about 1.5 mm. Combinations of the above-referencedranges are also possible. For example, in some embodiments, the outersheath tube may have an outside diameter of about 1.5 mm to about 2.2mm, or about 1.6 mm to about 2.1 mm, or about 1.65 to about 2 mm, orabout 1.7 mm to about 1.9 mm, or about 1.75 mm to about 1.85 mm.

In some embodiments, the outer sheath tube may have an inside diameterthat is larger than the outside diameter of the inner tube by at leastabout 0.08 mm, at least about 0.09 mm, at least about 0.1 mm, at leastabout 0.11 mm, or at least about 0.12 mm. In some embodiments, the outersheath tube may have an inside diameter that is larger than the outsidediameter of the inner tube by less than or equal to about 0.14 mm, lessthan or equal to about 0.12 mm, less than or equal to about 0.11 mm,less than or equal to about 0.1 mm, or less than or equal to about 0.09mm, or less than or equal to about 0.08 mm. Combinations of theabove-referenced ranges are also possible. For example, in someembodiments, the outer sheath tube may have an inside diameter that islarger than the outside diameter of the inner tube by at least about0.08 mm to about 0.12 mm, or about 0.09 mm to about 0.11 mm, or about0.095 mm to about 0.11 mm.

In some embodiments, the inner tube and/or the outer sheath tube mayhave a total length from a proximal end to a distal end of at leastabout 10 cm, at least about 20 cm, at least about 30 cm, at least about40 cm, at least about 45 cm, at least about 50 cm, at least about 55 cm,at least about 60 cm, or at least about 70 cm. In some embodiments, theinner tube and/or the outer sheath tube may have a total length from aproximal end to a distal end of less than or equal to about 70 cm, lessthan or equal to about 60 cm, less than or equal to about 55 cm, lessthan or equal to about 50 cm, less than or equal to about 45 cm, lessthan or equal to about 40 cm, less than or equal to about 30 cm, lessthan or equal to about 20 cm, or less than or equal to about 10 cm.Combinations of the above-referenced ranges are also possible. Forexample, in some embodiments, the inner tube and/or the outer sheathtube may have a total length from a proximal end to a distal end ofabout 20 cm to about 60 cm, or about 10 cm to about 70 cm, or about 30cm to about 50 cm, or about 40 cm to about 50 cm, or about 45 cm toabout 55 cm, or about 48 to about 52 cm, or about 50 to about 60 cm.

In some embodiments, the inner tube and/or the outer sheath tube may bemade from PTFE, other polymer, fluoropolymer or plastic material, orother suitable material that can be used to provide appropriate tubingstrength and/or torque transferences. In some embodiments, the innertube and/or the outer sheath tube may be made from a braided (steel orotherwise) PTFE tubing.

According to one aspect, in some embodiments, the device may include acomponent that may help to reinforce the connection between the needleand the inner tube. In one illustrative embodiment, shown in FIG. 29 ,the device includes a needle sheath 60 that receives the needle 10. Insome embodiments, the needle sheath 60 may serve to connect the needleto the inner tube and/or reinforce the connection between the needle andthe inner tube.

In some embodiments, the needle sheath 60 may include a needle sheathbody 66 and a collar 64. The outside diameter of the collar 64 may belarger than the outside diameter of the needle sheath body 66. As seenin FIGS. 30A and 30B, the needle 10 may extend through the needle sheath60. In some embodiments, the distal portion of the outer sheath tube maybe tapered in the distal direction to have a reduced inside diameter. Insome embodiments, the inside diameter of the outer sheath tube at thedistal end of the outer sheath tube may be smaller than the outsidediameter of the collar 64. As a result, due to contact between thecollar and the tapered inside diameter at the distal portion of theouter sheath tube, the collar may prevent the needle from further distalmovement relative to the outer sheath tube beyond a certain point. Insome cases, such an arrangement may help to prevent overextension of theneedle.

In some embodiments, the needle may be attached to the needle sheath bylaser welding, adhesive bonding, ultrasonic welding, or by any othersuitable attachment means. The needle may be attached to the collarand/or to the needle sheath body.

In some embodiments, such as that shown in FIG. 30A, the needle 10 hasan exposed portion having length L4 extending from the sheath 64. Insome embodiments, the length L4 may be at least about 5 mm, at leastabout 6 mm, at least about 7 mm, at least about 7.5 mm, at least about 8mm, at least about 8.5 mm, at least about 9 mm, at least about 10 mm, atleast about 11 mm, or at least about 12 mm. In some embodiments, lengthL4 may be less than or equal to about 15 mm, less than or equal to about12 mm, less than or equal to about 11 mm, less than or equal to about 10mm, less than or equal to about 9 mm, less than or equal to about 8.5mm, less than or equal to about 8 mm, less than or equal to about 7.5mm, less than or equal to about 7 mm, less than or equal to about 6 mm,or less than or equal to about 5 mm. Combinations of theabove-referenced ranges are also possible. For example, in someembodiments, length L4 may be about 5 mm to about 11 mm, or about 6 mmto about 10 mm, or about 7 mm to about 9 mm, or about 7.5 to about 8.5mm.

In some embodiments, as seen in FIGS. 31A and 31B, the needle sheath 60may have a channel 65 to receive the needle, the channel having adiameter D5. In some embodiments, the diameter D5 may be at least about0.45 mm, at least about 0.5 mm, at least about 0.55 mm, at least about0.6 mm, at least about 0.65 mm, at least about 0.7 mm, at least about0.75 mm, or at least about 0.8 mm. In some embodiments, the channel 65may have a diameter D5 of less than or equal to about 0.9 mm, less thanor equal to about 0.8 mm, less than or equal to about 0.7 mm, less thanor equal to about 0.65 mm, less than or equal to about 0.6 mm, or lessthan or equal to about 0.5 mm. Combinations of the above-referencedranges are also possible. For example, in some embodiments, the channelmay have a diameter D5 of about 0.45 mm to about 0.8 mm, or about 0.55mm to about 0.75 mm, or about 0.6 to about 0.7 mm.

The collar 64 and needle sheath body 66 may be a single monolithiccomponent. For example, the collar and needle sheath body may be weldedtogether or may be molded together. In some embodiments, the collar andneedle sheath body are formed separately and then attached together.

In some embodiments, the needle sheath may be attached to the innertube. In some embodiments, a distal end of the inner tube may bereceived within the channel of the needle sheath. In other embodiments,the proximal end of the needle sheath may be received within the innertube. The needle sheath may be attached to the inner tube by laserwelding, adhesive bonding, ultrasonic welding, or by any other suitableattachment means. In some embodiments, an intermediate coupling may beused to attach the inner tube to the needle sheath.

According to one aspect, the device handle may be used to actuate theneedle between a retracted position and an extended position. In someembodiments, the handle comprises two portions that cooperate with oneanother to actuate the needle. In some embodiments, the two portions ofthe handle are moveable relative to one another. In one embodiment, thefirst handle portion may be attached to the outer tube sheath, and theinner tube may extend through channels in both portions of the handle.The inner tube may attach to a syringe that connects to the secondportion of the handle. Movement of the second handle portion relative tothe first handle portion may move the inner tube relative to the outersheath tube, which may cause the inner tube and needle to move from aretracted position in which the needle is covered by the outer sheath,to an extended position in which the needle is exposed. As such, in someembodiments, the portions of the handle are moved relative to oneanother to actuate deployment of the needle.

One illustrative embodiment of a device handle is shown in FIG. 32 ,which depicts an enlarged view of the handle 100. The handle 100 mayinclude two portions, a leading portion 110 and a back portion 150. Insome embodiments, the leading portion 110 may have an opening thatreceives the back portion 150. As shown in FIG. 32 , the distal end ofthe leading portion 110 receives the proximal end of back portion 150.Alternatively, in some embodiments, the back portion may have an openingthat receives the leading portion.

A perspective view of the leading portion 110 is shown in FIG. 33A and atop-down view of the leading portion 110 is shown in FIG. 33B. In someembodiments, the leading portion 110 may attach to the outer tubesheath. The leading portion 110 may have a tubing connector 112 thatcouples the outer tube sheath to the leading portion 110. The tubingconnector 112 may be inserted into the proximal end of the outer tubesheath and may create a fluid-tight connection via an interference fit.Alternatively or in addition, a fluid-tight connection may be providedby or further supplemented by adhesive bonding, UV welding or othersuitable attachment means. As best seen in FIG. 33B, the leading portion110 may have a channel 115. The inner tube may be positioned within thechannel 115, and may be able to slide within the channel 115 relative tothe leading portion 110 and relative to the outer tube sheath. Theproximal end of the channel 115 may be sized and shaped to receive theback portion 150 of the handle. In FIG. 32 , the handle is shown in anassembled state where the back portion 150 is received in the leadingportion 110.

A perspective view of the back portion 150 is shown in FIG. 34A and atop-down view of the back portion 150 is shown in FIG. 34B. As best seenin FIG. 34B, in some embodiments, the back portion 150 includes achannel 165 through which the inner tube may extend. The back portion150 may include a luer fitting 170 or other connecting feature thatserves to connect the handle to a syringe or other composition-holdingcontainer. In some embodiments, an intermediate coupling between thehandle and the syringe is used to connect the handle to the syringe. Inother embodiments, the handle may directly connect to a syringe.

In some embodiments, the distal end of the back portion 150 is sized andshaped to fit within the channel 115 of the leading portion 110. Thedistal end of the back portion 150 may have arms 155 that can moverelative to one another. Each of the arms 155 may include a protrusion157. When the arms 155 are slid into the channel 115 of the leadingportion 110, the arms may be pressed radially inwardly toward oneanother due to contact between the protrusions 157 and the inner surfaceof the channel 115. As the arms proceed further into the channel 115,they may arrive at a pair of proximal openings 116 in the leadingportion 110 (the second proximal opening is not visible in FIG. 33A, asit is on the underside of the component). The proximal openings 116 maybe sized and shaped to receive the protrusions 157. When the protrusions157 reach the openings 116, the protrusions may snap into place into theopenings, as the arms 155 may be biased to return from its inwardlypressed state to an unstressed state. In some embodiments, duringmanufacturing, the device may be placed in this orientation, in whichthe protrusions of the arms are located within the proximal openings116.

A user may apply a force on the leading portion 110 and/or on the backportion 150 of the handle to force the protrusions 157 of the arms outof the openings 116 and move the leading portion 110 proximally towardsthe back portion 150. The arms 155 may be pressed radially inwardlytoward one another due to contact between the protrusions 157 and theinner surface of the channel 115. As the leading portion 110 is movedtoward the back portion 150, the protrusions 157 may encounter a pair ofdistal openings 114. As the openings 114 near the protrusions, theprotrusions 157 may snap into place into the openings 114, as the arms155 may be biased to return from its inwardly pressed state to anunstressed state.

In some embodiments, when the protrusions 157 are located within theproximal openings 116, the needle may be in the retracted position inwhich the needle is covered by the outer sheath tube. Pushing the backportion 150 of the handle distally forward further into the leadingportion 110 of the handle such that the protrusions 157 are moved intothe distal openings 114 may move the needle into the extended positionin which the needle is exposed and can penetrate into an injection site.A user may manipulate the portions of the handle to move the protrusions155 back and forth between the distal and proximal holes 114, 116 byapplying a threshold amount of force on one or both portions of thehandle in order to actuate the needle between retracted and extendedpositions.

According to one aspect, the handle may include features that aid inactuation and/or gripping of the handle. Such features may aid inone-handed operation of the handle.

As seen in FIG. 33A, in some embodiments, the leading portion 110 mayinclude protruding gripping features 122. In some embodiments, theleading portion 110 may include outwardly extending wings 120. Suchwings 120 may provide one or more surfaces against which a user may pullor push on to move the leading portion 110 distally away from the backportion 150 or proximally toward the back portion 150.

In some embodiments, the back portion 150 of the handle may havefeatures that aid in actuation and/or gripping of the handle. As seen inFIG. 34A, the back portion 150 may include protruding gripping features162, as well as outwardly extending wings 160. In some cases, a user mayhold onto the back portion 150 of the handle by gripping these featureswith a portion of one hand, and the rest of the hand may be used tomanipulate the leading portion 110. For example, the middle, ring andpinky fingers may wrap around the back portion 150, while the thumb andindex finger may be used to push and pull on the leading portion 110relative to the back portion 150. In some cases, the middle finger maybe used to interact with the leading portion 110 instead. As a result, auser may actuate the handle using one hand.

In some embodiments, as seen in FIG. 33B, the leading portion 110 of thehandle may have a total length L2 from proximal end to distal end. Insome embodiments, length L2 may be at least about 30 mm, at least about40 mm, at least about 45 mm, at least about 47 mm, at least about 50 mm,at least about 55 mm, or at least about 60 mm. In some embodiments,length L2 may be less than or equal to about 60 mm, less than or equalto about 55 mm, less than or equal to about 50 mm, less than or equal toabout 45 mm, less than or equal to about 40 mm, or less than or equal toabout 30 mm. Combinations of the above-referenced ranges are alsopossible. For example, in some embodiments, length L2 may be about 30 mmto about 60 mm, or about 40 mm to about 50 mm, or about 45 mm to about50 mm.

In some embodiments, as seen in FIG. 34B, the back portion 150 of thehandle may have a total length L3 from proximal end to distal end. Insome embodiments, length L3 may be at least about 30 mm, at least about40 mm, at least about 45 mm, at least about 50 mm, at least about 55 mm,or at least about 60 mm. In some embodiments, length L2 may be less thanor equal to about 60 mm, less than or equal to about 55 mm, less than orequal to about 50 mm, less than or equal to about 45 mm, less than orequal to about 40 mm, or less than or equal to about 30 mm. Combinationsof the above-referenced ranges are also possible. For example, in someembodiments, length L3 may be about 30 mm to about 60 mm, or about 40 mmto about 50 mm, or about 45 mm to about 55 mm.

In some embodiments, the handle may have a first overall length when theneedle is retracted, and a second overall length when the needle isexposed. In some embodiments, the first overall length may be at leastabout 6 cm, at least about 7 cm, at least about 8 cm, at least about 8.2cm, at least about 8.5 cm, at least about 9 cm or at least about 10 cm.In some embodiments, the first overall length may be less than or equalto about 10 cm, less than or equal to about 9 cm, less than or equal toabout 8.5 cm, less than or equal to about 8.2 cm, less than or equal toabout 8 cm, less than or equal to about 7 cm, or less than or equal toabout 6 cm. Combinations of the above-referenced ranges are alsopossible. For example, in some embodiments, the first overall length maybe about 6 cm to about 10 cm, or about 7 cm to about 9 cm, or about 8 cmto about 8.5 cm, or about 8.2 cm.

In some embodiments, the second overall length may be at least about 4cm, at least about 5 cm, about 6 cm, at least about 7 cm, at least about8 cm, at least about 8.2 cm, at least about 8.5 cm, or at least about 9cm. In some embodiments, the second overall length may be less than orequal to about 9 cm, less than or equal to about 8 cm, less than orequal to about 7.5 cm, less than or equal to about 7.3 cm, less than orequal to about 7 cm, or less than or equal to about 6 cm. Combinationsof the above-referenced ranges are also possible. For example, in someembodiments, the second overall length may be about 4 cm to about 9 cm,or about 6 cm to about 8 cm, or about 6.5 cm to about 7.5 cm, or about 7cm.

In some embodiments, the difference between the first overall length andthe second overall length may be at least about 2 cm, at least about 4cm, or at least about 6 cm. In some embodiments, the difference betweenthe first overall length and the second overall length may be less thanor equal to about 6 cm, less than or equal to about 4 cm, or less thanor equal to about 2 cm. Combinations of the above-referenced ranges arealso possible. For example, in some embodiments, the difference betweenthe first overall length and the second overall length may be about 2 to6 cm, or about 3 to 5 cm, or about 4 to 4.5 cm.

In some embodiments, the first overall length is greater than the secondoverall length.

In some embodiments, as seen in FIG. 22 , the delivery device 1 has atotal working length L7, which is the combined length of handle, tubingand needle when all assembled together and the needle is fully extended.In some embodiments, the total working length L7, is at least about 40cm, at least about 45 cm, at least about 50 cm, at least about 54 cm, atleast about 55 cm, at least about 60 cm, at least about 65 cm, or atleast about 70 cm. In some embodiments, the total working length L7 isless than or equal to about 70 cm, less than or equal to about 65 cm,less than or equal to about 60 cm, less than or equal to about 55 cm,less than or equal to about 54 cm, less than or equal to about 50 cm,less than or equal to about 45 cm, or less than or equal to about 40 cm.

In some embodiments, the delivery device has a priming volume of atleast about 600 μL, at least about 700 μL, at least about 750 μL, atleast about 800 μL, or at least about 850 μL. In some embodiments, thepriming volume is less than or equal to about 900 μL, less than or equalto about 850 μL, less than or equal to about 800 μL, less than or equalto about 750 μL, less than or equal to about 700 μL, or less than orequal to about 600 μL. Combinations of the above-referenced ranges arealso possible. For example, in some embodiments, the priming volume isabout 600 μL, to about 900 μL, or about 650 μL, to about 850 μL, orabout 700 μL, to about 800, or about 740 μL, to about 760 μL.

In some embodiments, the handle may be made from acrylonitrile butadienestyrene (ABS), other plastic, or other suitable material. In someembodiments, the handle is formed via injection molding.

In some embodiments, the delivery device may include a connecting tubeconnecting a proximal end of the inner tube to the syringe. The tube maybe sized to be received within the handle. In some cases, the connectingtube may help to facilitate flow of material from the syringe into theinner tubing. In some embodiments, the connecting tube is made of amaterial having a higher rigidity than that of the inner tube. Forexample, in some embodiments, the connecting tube is made of stainlesssteel or other metal or metal alloy. In some embodiments, the connectingtube comprises a hypotube. One illustrative embodiment of a connectingtube 140 is shown in FIG. 35 .

In some embodiments, the connecting tube may have a total length from aproximal end to a distal end of at least about 30 mm, at least about 40mm, at least about 45 mm, at least about 50 mm, at least about 55 mm, atleast about 60 mm, or at least about 70 mm. In some embodiments, theconnecting tube may have a total length from a proximal end to a distalend of less than or equal to about 70 mm, less than or equal to about 60mm, less than or equal to about 55 mm, less than or equal to about 50mm, less than or equal to about 45 mm, less than or equal to about 40mm, or less than or equal to about 30 mm. Combinations of theabove-referenced ranges are also possible. For example, in someembodiments, the connecting tube may have a total length from a proximalend to a distal end of about 30 mm to about 60 mm, or about 40 mm toabout 50 mm, or about 42 mm to about 48 mm, or about 43 mm to about 47mm.

In some embodiments, a connecting tube or a channel of the back portionand/or the leading portion of the handle may be tapered in the distaldirection. Without wishing to be bound by theory, a tapered connectingtube or channel may help to reduce shear stress of viscous material asthe material moves from the syringe to the inner tube.

In some embodiments, to administer an injectable composition, the tubingof a delivery device may be first threaded onto an endoscope orlaryngoscope. Once the endoscope or laryngoscope is positioned next to aregion of interest, the sliding portion of the handle may be moved toextend the inner tube and insert the needle into the region of interest.A syringe containing an injectable composition may then be attached tothe handle of the delivery device. A channel within the handle mayconnect the injectable composition to the inner tube for extrusion.After extrusion, the syringe may be removed from the handle and thesliding portion of the handle may be moved to retract the inner tube andremove the hollow needle from the region of interest. The deliverydevice and endoscope may then be removed.

Kit Comprising Delivery Device and any One of the Silk Fibroin Particlesor Compositions Described Herein

Further provided herein is a kit comprising any embodiment of thedelivery devices described herein and any embodiment of the compositionsor injectable compositions described herein. In some embodiments, thecomposition may be pre-loaded in or separately packaged from a syringe.

In some embodiments, a topical anesthetic can be blended with anyembodiment of the compositions or injectable compositions describedherein. In alternative embodiments, a topical anesthetic can be packagedin a separate container or in a separate syringe. For example, in someembodiments, it may be desirable to apply a topical anesthetic to atarget tissue to be treated prior to further treatment. An exemplaryanesthetic includes, but is not limited to, lidocaine. Dependent uponapplication, the kit can include syringes sizes from about 0.5 mL toabout 3 mL, or about 0.5 mL to about 1.5 mL, or about 0.5 mL to about 1mL.

In some embodiments, needle gauge can be adjusted according to theparticular injection site with an acceptable range of 18 to 30 gaugeneedles. For example, 26 to 30 gauge needles can be used for intradermalinjections.

In some embodiments, the kit can further comprise a plurality ofsyringes (each with a corresponding needle) containing any embodiment ofthe compositions or injectable compositions described herein. Eachsyringe can be individually packaged.

In some embodiments, the kit can further comprise a container containinga buffered solution or an injection carrier.

In some embodiments, the kit can further comprise at least oneadditional empty syringe. In some embodiments, the kit can furthercomprise at least one additional needle. In some embodiments, the kitcan further comprise at least one catheter or cannula.

The one or more syringes of the kit may contain an injectablecomposition comprising crosslinked hyaluronic acid and biocompatibleparticles having an average particle size of about 50 μm to about 1000μm, wherein the crosslinked hyaluronic acid has a crosslink density ofabout 4 mol % to about 30 mol %, wherein the biocompatible particles andthe crosslinked hyaluronic acid are present in a volume ratio of about5:95 to about 95:5 (e.g., about 60:40 to about 20:80).

In some embodiments, the composition is characterized in that a standarddeviation of extrusion force of the composition through a 18-30 gaugeneedle into air, as determined between about 50% extrusion volume andabout 90% extrusion volume, is less than about 40% of an averageextrusion force for the corresponding range of the extrusion volume.

In some embodiments, the composition is characterized in that astiffness of the composition is decreased by at least about 10% asmeasured between about 10% strain and about 90% strain.

Carriers

Any suitable carrier (e.g., first carrier, second carrier) that isbiocompatible with the particles (e.g., silk fibroin particles) or anyother components, if any, dispersed therein can be used. The particularcarrier(s) used may be chosen based on its ability to carry or deliverthe particles as described herein (e.g., silk fibroin particles). Insome embodiments, a carrier (e.g., first carrier, second carrier) isselected such that the combination of the particles or silk fibroinparticles and the carrier is injectable as described above, e.g., havinga particular average extrusion force as discussed above.

In some embodiments, a carrier (e.g., first carrier, second carrier) foruse in any one of the compositions described herein is apharmaceutically acceptable carrier. The phrase “pharmaceuticallyacceptable” refers to those compounds, materials, compositions, and/ordosage forms which are, within the scope of sound medical judgment,suitable for use in contact with the tissues of human beings and animalswithout excessive toxicity, irritation, allergic response, or otherproblem or complication, commensurate with a reasonable benefit/riskratio. The phrase “pharmaceutically acceptable carrier” as used hereinmeans a pharmaceutically acceptable material, composition or vehicle,such as a liquid or solid filler, diluent, excipient, solvent, media,encapsulating material, manufacturing aid (e.g., lubricant, talcmagnesium, calcium or zinc stearate, or stearic acid), or solventencapsulating material, involved in maintaining the stability,solubility, or activity of, silk fibroin particles and/or an activeagent, if any, dispersed therein. Each carrier must be “acceptable” inthe sense of being compatible with the other ingredients of theformulation and not injurious to the patient.

In some embodiments, the carrier (e.g., first carrier, second carrier)can be a biological carrier. Examples of such carriers suitable for usein any one of the compositions described herein include, but are notlimited to a glycosaminoglycan polymer (e.g., hyaluronic acid,crosslinked hyaluronic acid, keratan sulfate, chondroitin sulfate,heparin, and the like), an extracellular matrix such as a globular orfibrous protein polymer (e.g., collagen, elastin, fibronectin, etc.), ora biological fluid or concentrate (e.g., lipoaspirate, a bone marrowaspirate).

In some embodiments, the carrier (e.g., first carrier, second carrier)comprises a hyaluronic acid polymer (crosslinked and/ornon-crosslinked). In some embodiments, the carrier essentially consistsof a hyaluronic acid polymer (crosslinked and/or non-crosslinked). Insome embodiments, the hyaluronic acid polymer (non-crosslinked) may havean average molecular weight of at least about 200 kDa, at least about300 kDa, at least about 400 kDa, at least about 500 kDa, at least about600 kDa, at least about 700 kDa, at least about 800 kDa, at least about900 kDa, at least about 1 MDa, at least about 2 MDa, at least about 3MDa, at least about 4 MDa, or at least about 5 MDa. In some embodiments,the hyaluronic acid polymer (non-crosslinked) may have an averagemolecular weight of less than or equal to about 5 MDa, less than orequal to about 4 MDa, less than or equal to about 3 MDa, less than orequal to about 2 MDa, less than or equal to about 1 MDa, less than orequal to about 900 kDa, less than or equal to about 800 kDa, less thanor equal to about 700 kDa, less than or equal to about 600 kDa, lessthan or equal to about 500 kDa, less than or equal to about 400 kDa,less than or equal to about 300 kDa, or less than or equal to about 200kDa. Combinations of the above-referenced ranges are also possible. Forexample, in some embodiments, In some embodiments, the hyaluronic acidpolymer (non-crosslinked) may have an average molecular weight of about200 kDa to about 5 MDa, or about 300 kDa to about 4 MDa, or about 400kDa to about 3 MDa, or about 500 kDa to about 2 MDa. In someembodiments, the hyaluronic acid polymer (non-crosslinked) may have anaverage molecular weight of about 1 MDa or greater, e.g., 1 MDa, 1.5MDa, 2 MDa, 2.5 MDa, 3 MDa, 3.5 MDa, 4 MDa, 4.5 MDa, 5 MDa or higher. Insome embodiments, the hyaluronic acid polymer (crosslinked and/ornon-crosslinked) may have an average molecular weight of about 1 MDa orlower, e.g., 0.9 MDa, 0.8 MDa, 0.7 MDa, 0.6 MDa, 0.5 MDa, 0.4 MDa, 0.3MDa, 0.2 MDa, 0.1 MDa, or lower.

In some embodiments, the crosslinked matrix carrier (e.g., crosslinkedhyaluronic acid polymer) has an average molecular weight that is atleast about 2-fold, at least about 3-fold, at least about 4-fold, atleast about 5-fold, at least about 10-fold, at least about 25-fold, atleast about 50-fold, at least about 75-fold, or at least about 100-fold,higher than any of the average molecular weights provided herein for acorresponding non-crosslinked carrier (e.g., non-crosslinked hyaluronicacid polymer) used to form the crosslinked matrix carrier in thecomposition.

The average molecular weights provided herein for the carrier (e.g.,first carrier, second carrier) and/or hyaluronic acid polymer(crosslinked or non-crosslinked) can correspond to weight averagemolecular weights, number average molecular weights, or peak averagemolecular weights. In one set of the embodiments described herein, theaverage molecular weights provided herein for the carrier (e.g., firstcarrier, second carrier) and/or hyaluronic acid polymer (crosslinked ornon-crosslinked) correspond to weight average molecular weights.

In some embodiments, the carrier (e.g., first carrier, second carrier)can be a polymeric or a synthetic carrier. Examples of such carrierssuitable for use in any one of the compositions described hereininclude, but are not limited to biocompatible polymers such aspolyesters, poly(lactic acid) (PLA), poly(lactic-co-glycolic acid)(PLGA), poly(ethylene glycol) (PEG), and the like.

In some embodiments, the carrier is a shear-thinning material, e.g., ahyaluronic acid polymer. As used herein, the term “shear thinning” hasan ordinary meaning associated with the term, i.e., an effect where amaterial or fluid's viscosity decreases with an increasing strain orshear rate. For example, the viscosity of the carrier can be measured atvarying strain or shear rates, e.g., between about 2 s⁻¹ and about 30s⁻¹, or between about 3 s⁻¹ and about 25 s⁻¹, or between about 5 s⁻¹ andabout 25 s⁻¹.

The concentration of the carrier (e.g., first carrier, second carrier)can vary with the desired viscosity of the composition comprising silkfibroin particles and the carrier. Desirable ranges of dynamic viscositycan vary with different applications. For example, the compositionsdescribed herein for use in vocal fold tissue can have dynamic viscosityranging from about 10,000 Pas to about 1 Pas. Soft tissues in generalfollow similar trends. See, e.g., Borzacchiello, A. “RheologicalCharacterization of Vocal Folds after Injection Augmentation in aPreliminary Animal Study,” 2004, Journal of Bioactive and CompatiblePolymers; and Caton T., “Viscoelasticity of hyaluronan and nonhyaluronanbased vocal fold injectables: implications for mucosal versus muscleuse,” 2007, The Laryngoscope, the contents of each of which isincorporated herein by reference in their entireties. Viscosity of acomposition can be measured, for example, by a parallel plate, shearrheology test, in which steady state shear rate is varied, e.g., from0-23 s⁻¹, to observe changes in viscosity.

In some embodiments where a hyaluronic acid polymer is selected as thecarrier, the concentration of the hyaluronic acid polymer can vary withthe desired viscosity of the composition as described above. Forexample, the hyaluronic acid polymer may have a concentration of atleast about 0.1% (w/v), at least about 0.5% (w/v), at least about 1%(w/v), at least about 2% (w/v), at least about 3% (w/v), at least about4% (w/v), at least about 5% (w/v), at least about 6% (w/v), at leastabout 7% (w/v), at least about 8% (w/v), at least about 9% (w/v), or atleast about 10% (w/v). In some embodiments, the hyaluronic acid polymermay have a concentration of less than or equal to about 10% (w/v), lessthan or equal to about 9% (w/v), less than or equal to about 8% (w/v),less than or equal to about 7% (w/v), less than or equal to about 6%(w/v), less than or equal to about 5% (w/v), less than or equal to about4% (w/v), less than or equal to about 3% (w/v), less than or equal toabout 2% (w/v), less than or equal to about 1% (w/v), less than or equalto about 0.5% (w/v), or less than or equal to about 0.1% (w/v).Combinations of the above-referenced ranges are also possible. Forexample, in some embodiments, the hyaluronic acid polymer may have aconcentration of about 0.1% (w/v) to about 10% (w/v), about 1% (w/v) toabout 10% (w/v), about 1% (w/v) to about 8% (w/v), about 1% (w/v) toabout 6% (w/v), or about 1% (w/v) to about 5% (w/v). In someembodiments, the hyaluronic acid polymer may have a concentration ofabout 1% (w/v), about 2% (w/v), about 3% (w/v), about 4% (w/v), about 5%(w/v), about 6% (w/v), about 7% (w/v), about 8% (w/v), about 9% (w/v),or about 10% (w/v).

In some embodiments where the carrier comprises more than two types ofcarriers, and the first carrier comprises hyaluronic acid of anymolecular weight described above or within a range described above, thesecond carrier comprises hyaluronic acid with an average molecularweight (e.g., weight average molecular weight) of at least about 200kDa, at least about 300 kDa, at least about 400 kDa, at least about 500kDa, at least about 600 kDa, at least about 700 kDa, at least about 800kDa, at least about 900 kDa, or at least about 1 MDa. In someembodiments, the second carrier comprises hyaluronic acid with anaverage molecular weight (e.g., weight average molecular weight) of lessthan or equal to about 1 MDa, less than or equal to about 900 kDa, lessthan or equal to about 800 kDa, less than or equal to about 700 kDa,less than or equal to about 600 kDa, less than or equal to about 500kDa, less than or equal to about 400 kDa, less than or equal to about300 kDa, or less than or equal to about 200 kDa. Combinations of theabove-referenced ranges are also possible. In some embodiments, thesecond carrier can comprise hyaluronic acid with a molecular weight(e.g., weight average molecular weight) of about 200 kDa to about 1 MDa,or about 300 kDa to about 1 MDa, or about 400 kDa to about 1 MDa, orabout 500 kDa to about 1 MDa. In some embodiments, the second carriercan comprise hyaluronic acid with a molecular weight (e.g., weightaverage molecular weight) of less than 1 MDa or lower, including, e.g.,1 MDa, 0.9 MDa, 0.8 MDa, 0.7 MDa, 0.6 MDa, 0.5 MDa, 0.4 MDa, 0.3 MDa,0.2 MDa, 0.1 MDa, or lower. The concentration of hyaluronic acid in thefirst carrier and/or the second carrier can be the same or different,for example, within the ranges as described above for a single carrier.

In other embodiments, one or more additional carriers (e.g., a thirdcarrier) may be present in the composition. For example, the thirdcarrier may comprise hyaluronic acid of an average molecular weight thatis different from that of the first carrier and the second carrier.Alternatively, the third carrier may comprise a polymer that isdifferent from that of the first carrier and/or the second carrier, or atissue. In such embodiments, the first and second carriers may be onespresent in the highest amounts with respect to all carriers in thecomposition.

Active Agents

In some embodiments, the compositions or injectable compositions and/orthe particles (e.g., silk fibroin particles) as described herein canfurther comprise at least one active agent. The active agent can bemixed, dispersed, or suspended in any embodiment of the compositions orinjectable compositions described herein, including the particles (e.g.,silk fibroin particles) and/or the carrier, and/or the active agent canbe distributed or embedded in any embodiment of the particles (e.g.,silk fibroin particles). In some embodiments, the active agent can bedistributed, embedded or encapsulated in the particles (e.g., silkfibroin particles). In some embodiments, the active agent can be coatedon surfaces of the particles (e.g., silk fibroin particles). In someembodiments, the active agent can be mixed with the particles (e.g.,silk fibroin particles) to form an injectable composition. The term“active agent” can also encompass combinations or mixtures of two ormore active agents, as described below. Examples of active agentsinclude, but are not limited to, a biologically active agent (e.g., antherapeutic agent, an anesthetic, a cell growth factor, a peptide, apeptidomimetic, an antibody or a portion thereof, an antibody-likemolecule, nucleic acid, a polysaccharide, and any combinations, cells,stem cells, biological fluids, immune suppressors, antibacterial agents,anti-inflammatory agents, analgesics, etc.), a cosmetically active agent(e.g., an anti-aging agent, an anti-free radical agent, an anti-oxidant,a hydrating agent, a whitening agent, a colorant, a depigmenting agent,a sun-blocking agent, a muscle relaxant, etc.), a cell attachment agent(e.g., collagen, crosslinked hyaluronic acid/collagen, integrin-bindingmolecules, chitosan, elastin, fibronectin, vitronectin, laminin,proteoglycans, any derivatives thereof, any peptide or oligosaccharidevariants), and any combinations thereof.

The term “biologically active agent” as used herein refers to anymolecule which exerts at least one biological effect in vivo. Forexample, the biologically active agent can be a therapeutic agent totreat or prevent a disease state or condition in a subject. Examples ofbiologically active agents include, without limitation, peptides,peptidomimetics, aptamers, antibodies or a portion thereof,antibody—like molecules, nucleic acids (DNA, RNA, siRNA, shRNA),polysaccharides, enzymes, receptor antagonists or agonists, hormones,growth hormones, growth factors, cell signaling factors, autogenous bonemarrow, antibiotics, antimicrobial agents, small molecules andtherapeutic agents. The biologically active agents can also include,without limitations, anti-inflammatory agents, anesthetics, and activeagents that stimulate tissue healing, formation, and/or ingrowth, cellrecruitment, integration into surrounding tissue matrix, and/or regrowthof natural tissues, and any combinations thereof. Cells, living tissuesor tissue components such as lipoaspirate, extracellular matrixcomponents can be included in any embodiment of the compositions,injectable compositions and/or particles (e.g., silk fibroin particles)described herein.

Anti-inflammatory agents can include, but are not limited to, naproxen,sulindac, tolmetin, ketorolac, celecoxib, ibuprofen, diclofenac,acetylsalicylic acid, nabumetone, etodolac, indomethacin, piroxicam,cox-2 inhibitors, ketoprofen, antiplatelet medications, salsalate,valdecoxib, oxaprozin, diflunisal, flurbiprofen, corticosteroids, MMPinhibitors and leukotriene modifiers or combinations thereof.

Agents that increase formation of new tissues and/or stimulates healingor regrowth of native tissue at the site of injection can include, butare not limited to, fibroblast growth factor (FGF), transforming growthfactor-beta (TGF-β, platelet-derived growth factor (PDGF), epidermalgrowth factors (EGFs), connective tissue activated peptides (CTAPs),osteogenic factors including bone morphogenic proteins, heparin,angiotensin II (A-II) and fragments thereof, insulin-like growthfactors, tumor necrosis factors, interleukins, colony stimulatingfactors, erythropoietin, nerve growth factors, interferons, biologicallyactive analogs, fragments, and derivatives of such growth factors, andany combinations thereof.

Anesthetics can include, but are not limited to, those used in caudal,epidural, inhalation, injectable, retrobulbar, and spinal applications,such as bupivacaine, lidocaine, benzocaine, cetacaine, ropivacaine, andtetracaine, or combinations thereof.

In some embodiments, the one or more active agents included in thecompositions and/or particles (e.g., silk fibroin particles) describedherein may be cosmetically active agents. By the term “cosmeticallyactive agent” is meant a compound that has a cosmetic or therapeuticeffect on the skin, hair, or nails, e.g., anti-aging agents, anti-freeradical agents, lightening agents, whitening agents, depigmentingagents, darkening agents such as self-tanning agents, colorants,anti-acne agents, shine control agents, anti-microbial agents,anti-inflammatory agents, anti-mycotic agents, anti-parasite agents,external analgesics, sun-blocking agents, photoprotectors, antioxidants,keratolytic agents, detergents/surfactants, moisturizers, nutrients,vitamins, energy enhancers, anti-perspiration agents, astringents,deodorants, hair removers, firming agents, anti-callous agents, musclerelaxants, agents for hair, nail, and/or skin conditioning, and anycombination thereof.

In one embodiment, the cosmetically active agent can be selected from,but not limited to, the group consisting of hydroxy acids, benzoylperoxide, sulfur resorcinol, ascorbic acid, D-panthenol, hydroquinone,octyl methoxycinnamate, titanium dioxide, octyl salicylate, homosalate,avobenzone, polyphenolics, carotenoids, free radical scavengers,ceramides, polyunsaturated fatty acids, essential fatty acids, enzymes,enzyme inhibitors, minerals, hormones such as estrogens, steroids suchas hydrocortisone, 2-dimethylaminoethanol, copper salts such as copperchloride, coenzyme Q10, lipoic acid, amino acids such a proline andtyrosine, vitamins, lactobionic acid, acetyl-coenzyme A, niacin,riboflavin, thiamin, ribose, electron transporters such as NADH andFADH2, and other botanical extracts such as aloe vera, feverfew, andsoy, and derivatives and mixtures thereof. Examples of vitamins include,but are not limited to, vitamin A, vitamin Bs (such as vitamin B3,vitamin B5, and vitamin B12), vitamin C, vitamin K, and vitamin E, andderivatives thereof.

In one embodiment, the one or more cosmetically active agents includedin the compositions and/or particles (e.g., silk fibroin particles) maybe antioxidants. Examples of antioxidants include, but are not limitedto, water-soluble antioxidants such as sulfhydryl compounds and theirderivatives (e.g., sodium metabisulfite and N-acetyl-cysteine), lipoicacid and dihydrolipoic acid, resveratrol, lactoferrin, ascorbic acid,and ascorbic acid derivatives (e.g., ascorbyl palmitate and ascorbylpolypeptide). Oil-soluble antioxidants suitable for use in thecompositions described herein include, but are not limited to, butylatedhydroxytoluene, tocopherols (e.g., tocopheryl acetate), tocotrienols,and ubiquinone. Natural extracts containing antioxidants suitable foruse in the injectable compositions described herein, include, but notlimited to, extracts containing flavonoids and isoflavonoids and theirderivatives (e.g., genistein and diadzein), and extracts containingresveratrol. Examples of such natural extracts include grape seed, greentea, pine bark, and propolis.

In some embodiments, the active agents can be cell attachment agents.Examples of cell attachment agents include, but are not limited to,hyaluronic acid, collagen, crosslinked hyaluronic acid/collagen, anintegrin-binding molecule, chitosan, elastin, fibronectin, vitronectin,laminin, proteoglycans, any derivatives thereof, and any combinationsthereof.

In some embodiments, the compositions or injectable compositions and/orparticles (e.g., silk fibroin particles) can further comprise at leastone additional material for soft tissue augmentation, e.g., additionalfiller materials, including, but not limited to, poly(methylmethacrylate) microspheres, hydroxyapatite, poly(L-lactic acid),collagen, elastin, and glycosaminoglycans, and/or hyaluronic acid.

In some embodiments where the compositions or injectable compositionsare formulated for use as dermal fillers, the compositions or injectablecompositions may further comprise a commercial dermal filler productsuch as DYSPORT®, COSMODERM®, EVOLENCE®, RADIESSE®, RESTYLANE®,JUVEDERM® (from Allergan), SCULPTRA®, PERLANE®, and CAPTIQUE®, and anycombinations thereof.

In some embodiments, the compositions or injectable composition and/orsilk fibroin particles can comprise metallic nanoparticles (e.g., butnot limited to, gold nanoparticles), optical molecules (e.g., but notlimited to, fluorescent molecules, and/or quantum dots), and any otherart—recognized contrast agent, e.g., for biomedical imaging.

Exemplary Methods of Use

The compositions and/or injectable compositions described herein can beused in a variety of medical uses, including, without limitation,fillers for tissue space, templates for tissue reconstruction oringrowth, scaffolds for cells in tissue engineering applications, and/oras a vehicle/carrier for drug delivery. Any embodiment of thecompositions or injectable compositions injected into a tissue to berepaired or augmented can act as a scaffold to mimic the extracellularmatrices (ECM) of the body, and/or promote tissue ingrowth. The scaffoldcan serve as both a physical support and/or an adhesive template forcells to proliferate therein. In some embodiments, the compositions orinjectable compositions do not comprise cells. However, in thoseembodiments, the compositions or injectable compositions can comprisecell attachment agents, e.g., collagen, and/or chemotactants, e.g.,growth factors, that can attract host cells and support the cellproliferation. Such cell attachment agents can be dispersed in thecarrier and/or silk fibroin particles of the compositions or injectablecompositions. In alternative embodiments, the silk fibroin particles canbe seeded with cells prior to administration to a target tissue to berepaired or augmented.

In some embodiments, provided herein are compositions and/or injectablecompositions that can be used to fill, volumize, and/or regenerate atissue in need thereof. The injectable compositions can generally beused for tissue filling or volumizing, soft tissue augmentation,replacement, cosmetic enhancement and/or tissue repair in a subject.Additionally, the injectable compositions can be used for filling of anytissue void or indentation that are either naturally formed (e.g.,aging) or created by surgical procedure for removal of tissue (e.g., adermal cyst or a solid tumor), corticosteroid treatment, immunologicreaction resulting in lipoatrophy, tissue damage resulting from impactinjuries or therapeutic treatment (e.g., radiotherapy or chemotherapy).The injectable compositions can also be used to raise scar depressions.

In certain embodiments, the injectable compositions can be used for softtissue augmentation. As used herein, by the term “augmenting” or“augmentation” is meant increasing, filling in, restoring, enhancing orreplacing a tissue. In some embodiments, the tissue can lose itselasticity, firmness, shape and/or volume. In some embodiments, thetissue can be partially or completely lost (e.g., removal of a tissue)or damaged. In those embodiments, the term “augmenting” or“augmentation” can also refer to decreasing, reducing or alleviating atleast one symptom or defect in a tissue (for example, but not limitedto, loss of elasticity, firmness, shape and/or volume in a tissue;presence of a void or an indentation in a tissue; loss of function in atissue) by injecting into the tissue with at least one injectablecomposition described herein. In such embodiments, at least one symptomor defect in a tissue can be decreased, reduced or alleviated by atleast about 30%, at least about 40%, at least about 50%, at least about60%, at least about 70%, at least about 80% or higher, as compared to notreatment. In some embodiments, at least one symptom or defect in atissue can be decreased, reduced or alleviated by at least about 90%, atleast about 95%, at least about 97%, or higher, as compared to notreatment. In some embodiments, at least one symptom or defect in atissue can be decreased, reduced or alleviated by 100% (defect-free orthe defect is undetectable by one of skill in the art), as compared tono treatment. In other embodiments, the tissue can be augmented toprevent or delay the onset of defect manifestation in a tissue, e.g.,loss of elasticity, firmness, shape and/or volume in a tissue, or signsof wrinkles. As used herein, the phrase “soft tissue augmentation” isgenerally used in reference to altering a soft tissue structure,including but not limited to, increasing, filling in, restoring,enhancing or replacing a tissue, e.g., to improve the cosmetic oraesthetic appearance of the soft tissue. Examples of soft tissueaugmentation include, but are not limited to, dermal tissueaugmentation; filling of lines, folds, wrinkles, minor facialdepressions, and cleft lips, especially in the face and neck; correctionof minor deformities due to aging or disease, including in the hands andfeet, fingers and toes; augmentation of the vocal cords or glottis torehabilitate speech; dermal filling of sleep lines and expression lines;replacement of dermal and subcutaneous tissue lost due to aging; lipaugmentation; filling of crow's feet and the orbital groove around theeye; chin augmentation; augmentation of the cheek and/or nose; bulkingagent for periurethral support, filling of indentations in the softtissue, dermal or subcutaneous, due to, e.g., overzealous liposuction orother trauma; filling of acne or traumatic scars; filling of nasolabiallines, nasoglabellar lines and intraoral lines. In some embodiments, thecompositions or injectable compositions described herein can be used totreat facial lipodystrophies.

In some embodiments, the compositions or injectable compositions can beused for soft tissue repair. The term “repair” or “repairing” as usedherein, with respect to a tissue, refers to any correction,reinforcement, reconditioning, remedy, regenerating, filling of a tissuethat restores volume, shape and/or function of the tissue. In someembodiments “repair” includes full repair and partial repair. Forexample, the volume, shape and/or function of a tissue to be repairedcan be restored by at least about 30%, at least about 40%, at leastabout 50%, at least about 60%, at least about 70%, at least about 80% orhigher within a certain period of time (e.g., within about 12 months,within about 9 months, within about 6 months, within about 3 months orshorter), as compared to no treatment. In some embodiments, the volume,shape and/or function of a tissue to be repaired can be restored by atleast about 90%, at least about 95%, at least about 97%, or higher,within a certain period of time (e.g., within about 12 months, withinabout 9 months, within about 6 months, within about 3 months orshorter), as compared to no treatment. In some embodiments, the volume,shape and/or function of a tissue to be repaired can be restored by 100%(defect—free or the defect is undetectable by one of skill in the art)within a certain period of time (e.g., within about 12 months, withinabout 9 months, within about 6 months, within about 3 months orshorter), as compared to no treatment. In various embodiments, theinjectable compositions can be used to repair any soft tissues discussedearlier, e.g., skin, and any soft tissues amenable for soft tissueaugmentation. Without wishing to be bound by theory, the injectablecompositions described herein can promote tissue ingrowth, which mayultimately shorten repair time. For example, tissue or cellular ingrowthinto the pores of the silk fibroin particles described herein canimprove the healing response.

The compositions and/or injectable compositions described herein canalso be used for filling a tissue located at or near a prostheticimplant, for example, but not limited to, a conventional breast implantor knee replacement implant. In some embodiments, the compositionsand/or injectable compositions can be used to interface between aprosthetic implant and a tissue, e.g., to fill a void between theprosthetic implant and the tissue, and/or to prevent the tissue indirect contact with the prosthetic implant. By way of example only,after placing a prosthetic implant (e.g., a breast implant) in asubject, an injectable composition described herein can be introduced ator adjacent to the implant to fill any void between the implant and thetissue (e.g., breast tissue) and/or “sculpt” the tissue for a morenatural look.

In any of the uses described herein, the compositions and/or injectablecompositions described herein can be combined with cells for purposes ofa biologically enhanced augmentation and/or tissue ingrowth. Cells canbe dispersed in the carrier and/or silk fibroin particles. Cells can becollected from a multitude of hosts including but not limited to humanautograft tissues, or transgenic mammals. More specifically, human cellsused can comprise cells selected from stem cells (e.g.,adipocyte—derived stem cells), fibroblasts, lipocytes, assortedimmunocytes, cells from lipoaspirate or any combinations thereof.

In some embodiments, administering the cells (e.g., stem cells) with anyembodiment of the compositions and/or injectable compositions describedherein can enhance or accelerate host integration and/or tissueformation over time. The cells can be dispersed in any embodiment of thecompositions and/or injectable compositions described herein, or theycan be administered prior to, concurrently with, or after thecomposition is introduced into a target site. Without wishing to bebound by theory, the cells can secrete pro-angiogenic factors and/orgrowth factors at the target site. As the tissue regenerates or remodelsto fill up a void or repair a defect, the silk fibroin particles and/orcarrier matrix can degrade accordingly. In some embodiments, the silkfibroin particles and/or carrier matrix can integrate with theregenerated host tissue.

In some aspects, the compositions and/or injectable compositionsdescribed herein can be used as tissue space fillers or bulking agentsfor treating a defect in a soft tissue of a subject, e.g., for softtissue augmentation and/or ingrowth. Accordingly, methods for augmentingor regenerating different soft tissues are provided herein. In someembodiments, such a method comprises injecting to a site of defect in asoft tissue a composition comprising silk fibroin particles of anyembodiments or aspects described herein and a carrier, or a compositionof any embodiments or as aspects described herein.

In some embodiments, a method of administering a composition to asubject may include

inserting a needle and a catheter of a delivery device into the subject,where the needle is coupled to and in fluid communication with thecatheter. The method may include moving the needle toward an injectionsite of the subject and actuating a handle of the delivery device tomove the needle from a retracted position to an extended position, whereactuating the handle comprises sliding a first portion of the handlerelative to a second portion of the handle from a first discreteposition to a second discrete position. The method may include insertingthe needle into the injection site, and the method may includedelivering a composition comprising silk fibroin particles through thecatheter and the needle into the injection site.

In some embodiments, a method of administering a composition to asubject may include inserting a needle and a catheter trans-orally ortrans-nasally into the subject, the needle being coupled to and in fluidcommunication with the catheter. The method may include moving theneedle toward a vocal fold of the subject, inserting the needle into thevocal fold, and delivering a composition comprising particles throughthe catheter and the needle into the vocal fold.

In some embodiments involving the methods of soft tissue augmentationdescribed herein, the compositions or injectable compositions areinjected through a 18-30 gauge needle (e.g., 18, 19, 20, 21, 22, 23, 24,25, 26, 27, 28, 29, or 30) such that a standard deviation of extrusionforce of the composition through a 18-30 (e.g., 18, 19, 20, 21, 22, 23,24, 25, 26, 27, 28, 29, or 30) gauge needle, as determined between about50% extrusion volume and about 90% extrusion volume, is less than about40%, less than about 35%, less than about 30%, less than about 25%, lessthan about 20%, less than about 15%, less than about 10%, less thanabout 5%, or less than about 1%, of an average extrusion force for thecorresponding range of the extrusion volume (i.e., about 50%-about 90%extrusion volume). In some embodiments, the standard deviation ofextrusion force of the composition through a 18-30 (e.g., 18, 19, 20,21, 22, 23, 24, 25, 26, 27, 28, 29, or 30) gauge needle, as determinedbetween about 50% extrusion volume and about 90% extrusion volume, is atleast about 0.1%, at least about 0.5%, at least about 1%, at least about5%, at least about 10%, at least about 15%, or at least about 20%, of anaverage extrusion force for the corresponding range of the extrusionvolume (i.e., about 50%-about 90% extrusion volume). Combinations of theabove-referenced ranges are also possible. For example, in someembodiments, the standard deviation of extrusion force of thecomposition through a 18-30 (e.g., 18, 19, 20, 21, 22, 23, 24, 25, 26,27, 28, 29, or 30) gauge needle, as determined between about 50%extrusion volume and about 90% extrusion volume, is about 0.1% to about40%, or about 1% to about 20%, or about 1% to about 15%, of an averageextrusion force for the corresponding range of the extrusion volume(i.e., about 50%-about 90% extrusion volume).

In some embodiments involving the methods of soft tissue augmentationdescribed herein, the compositions or injectable compositions areinjected through a 18-30 gauge needle (e.g., 18, 19, 20, 21, 22, 23, 24,25, 26, 27, 28, 29, or 30) using an average extrusion force of no morethan about 60 N, e.g., no more than about 55 N, no more than about 50 N,no more than about 45 N, no more than about 40 N, no more than about 35N, no more than about 30 N, no more than about 25 N, no more than about20 N, no more than about 15 N, no more than about 10 N, or no more thanabout 5 N. In some embodiments, the average extrusion force can be atleast about 5 N, at least about 6 N, at least about 7 N, at least about8 N, at least about 9 N, at least about 10 N, at least about 15 N, atleast about 20 N, at least about 25 N, at least about 30 N, at leastabout 35 N, at least about 40 N, at least about 45 N, at least about 50N, at least about 55 N, or at least about 60 N. Combinations of theabove-referenced ranges are also possible. For example, in someembodiments, the average extrusion force can range from about 5 N toabout 60 N, from about 10 N to about 60 N, or from about 5N to about30N, or from about 5N to about 25N, or about 5 N to about 20 N, or about5N to about 15N, or about 5N to about 10 N.

In some embodiments of any one of the methods and/or compositionsdescribed herein, the silk fibroin particles provide a bulking effect(e.g., increasing the elasticity, stiffness, and/or density of a softtissue) to the soft tissue by maintaining up to about 90%, or up toabout 85%, or up to about 80%, or up to about 75%, or up to about 70%,or up to about 60%, or up to about 50%, of the particles' originalvolume (e.g., injected volume) for at least about 3 months or longer(including, e.g., at least about 4 months, at least about 5 months, atleast about 6 months, at least about 7 months, at least about 8 months,at least about 9 months, at least about 10 months, at least about 11months, at least about 12 months or longer) after injection (e.g., up toabout 24 months after injection). In some embodiments, the silk fibroinparticles can maintain at least about 20%, at least about 30%, at leastabout 40%, at least about 50%, at least about 60%, at least about 70%,at least about 80%, or at least about 90%, of the particles' originalvolume (e.g., injected volume) for at least about 3 months or longer(including, e.g., at least about 4 months, at least about 5 months, atleast about 6 months, at least about 7 months, at least about 8 months,at least about 9 months, at least about 10 months, at least about 11months, at least about 12 months or longer) after injection (e.g., up toabout 36 months after injection). Combinations of the above-referencedranges are also possible. For example, in some embodiments, the silkfibroin particles can maintain about 20% to about 90% or about 30% toabout 80%, or about 40% to about 70% of the particles' original volume(e.g., injected volume) for at least about 3 months or longer(including, e.g., at least about 4 months, at least about 5 months, atleast about 6 months, at least about 7 months, at least about 8 months,at least about 9 months, at least about 10 months, at least about 11months, at least about 12 months or longer) after the injection (e.g.,up to about 36 months after injection).

In some embodiments of any one of the methods described herein, thecomposition and or injectable composition comprises (i) silk fibroinparticles and (ii) a carrier comprising any one or more of aglycosaminoglycan polymer (e.g., crosslinked HA or non-crosslinked HA),an extracellular matrix, a polysaccharide, or a fibrous protein polymerdescribed herein (including specific examples of each as describedherein).

In some embodiments of any one of the methods described herein, the silkfibroin particles have an average particle size in one or more rangesdescribed herein, e.g., about 200 μm to about 1000 μm, about 250 μm toabout 850 μm, about 300 μm to about 800 μm, about 400 μm to about 600μm, about 250 μm to about 450 μm, 200 μm to about 500 μm, or about 300μm to about 450 μm. In some embodiments of any one of the methodsdescribed herein, the silk fibroin particles have an average size ofabout 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, or1000 μm. Different sized particles can be chosen depending the volume ofa void to be filled or a defect to be treated. In general, smallparticles can be used for small defects, while larger particles can beused for larger defects.

The methods described herein can be applied to treat different softtissues for small volume bulking or large volume bulking applications,including but not limited to, a skin tissue, e.g., a facial skin tissue,a bladder tissue (e.g., a urethra), a cervical tissue, a vocal foldtissue, a breast tissue, or a buttock tissue. Other applications arealso possible, for example, stationary phases for liquid chromatographyand/or embolization therapy (occlusion of vessels to preventhemorrhaging).

For example, in some embodiments for large volume bulking applications(e.g., but not limited to breast reconstruction, buttock reconstruction,and treatment of lipodystrophy), the composition of any embodimentdescribed herein can be injected in an amount of at least about 3 cm³ orlarger (including, e.g., at least about 5 cm³, at least about 10 cm³, atleast about 20 cm³, at least about 30 cm³, at least about 40 cm³, atleast about 50 cm³, at least about 60 cm³, at least about 70 cm³, atleast about 80 cm³, at least about 90 cm³, at least about 100 cm³, atleast about 200 cm³, at least about 300 cm³, at least about 400 cm³, atleast about 500 cm³, or at least about 600 cm³. In some embodiments, thecomposition may be injected in an amount of no more than about 600 cm³,no more than about 500 cm³, no more than about 400 cm³, no more thanabout 300 cm³, no more than about 200 cm³, no more than about 100 cm³,no more than about 90 cm³, no more than about 80 cm³, no more than about70 cm³, no more than about 60 cm³, no more than about 50 cm³, no morethan about 40 cm³, no more than about 30 cm³, no more than about 20 cm³,no more than about 10 cm³, or no more than about 5 cm³. Combination ofthe above-referenced are also possible. For example, the amount of thecomposition injected into a target site may be of about 3 cm³ to about600 cm³, or about or 3 cm³ to about 500 cm³, or about 5 cm³ to about 500cm³, or about 10 cm³ to about 500 cm³. In these embodiments, thecomposition can be injected in an amount that is sufficient to fill andconform to the shape of a void at the target site. In these embodiments,the method may optionally further comprise allowing cells from tissuesurrounding the target site to interact with the silk fibroin particles,wherein the silk fibroin particles maintain at least about 30%(including, e.g., at least about 40%, at least about 50%, at least about60%, at least about 70% or higher) of their original volume (e.g.,injected volume) for at least about 9 months (including, e.g., at leastabout 10 months, at least about 11 months, at least about 12 months, atleast about 1.5 years, at least about 2 years or longer) after theinjection, thereby augmenting or regenerating the soft tissue. In someembodiments, the silk fibroin particles maintain at least 30%(including, e.g., at least about 40%, at least about 50%, at least about60%, at least about 70% or higher) of their original volume (e.g.,injected volume) of their volume for at least 12 months or longer afterthe injection.

In some embodiments involving large volume bulking applications, thecomposition is injected through a 18-21 gauge needle (e.g., 18, 19, 20,or 21 gauge needle) using an average extrusion force of no more than 60N. For example, in some embodiments, the average extrusion force canrange from about 5 N to about 60 N, from about 10 N to about 60 N, orfrom about 5N to about 30N, or from about 5N to about 25N, or about 5 Nto about 20 N, or about 5N to about 15N, or about 5N to about 10 N.

In other embodiments for small volume bulking applications, e.g., wherethe site of defect is not more than 3 cm³, the composition is injectedwith a 21-30 gauge needle using an average extrusion force of no morethan 30 N. For example, in some embodiments, the average extrusion forcecan range from about 5 N to about 30 N, from about 10 N to about 30 N,or from about 10N to about 25N, or from about 5N to about 25N, or about5 N to about 20 N, or about 5N to about 15N, or about 5N to about 10 N.Examples of small volume bulking applications include, but are notlimited to a dermal filler for skin tissue (e.g., treatment of facialskin tissue having a facial line, or wrinkle, or a scar to be filled),bulking of urethra (e.g., treatment for stress-urinary incontinence),bulking of cervical tissue (e.g., treatment for cervical insufficiency),and bulking of a vocal fold tissue (e.g., correction of vocal foldparalysis or other causes of vocal fold insufficiency).

In some embodiments, any of the methods and/or compositions orinjectable compositions described herein are used to treat a facial skintissue. For example, any embodiment of the compositions or injectablecompositions described herein can be injected to a facial line orwrinkle, or a scar. Thus, in some embodiments, the compositions and/orinjectable compositions described herein can be used as a dermal filler.The dermal filler comprising any embodiment of the compositions and/orinjectable composition can be modulated for particle compressibility,elasticity, softness, and/or opacity through alteration of silk fibroinconcentration and/or carrier matrix. The dermal filler can be used toimprove skin appearance or condition, including, but not limited to,rehydrating the skin, providing increased elasticity to the skin,reducing skin roughness, making the skin tauter, reducing or eliminatingstretch lines or marks, giving the skin better tone, shine, brightness,and/or radiance, reducing or eliminating wrinkles in the skin, providingwrinkle resistance to the skin and replacing loss of soft tissue.

Accordingly, another aspect described herein provides a method ofimproving a condition and/or appearance of skin in a subject in needthereof. Non-limiting examples of a skin condition or and/or appearanceinclude dehydration, lack of skin elasticity, roughness, lack of skintautness, skin stretch line and/or marks, skin paleness, and skinwrinkles. The method comprises injecting any embodiment of thecompositions or injectable compositions described herein into a dermalregion of the subject, wherein the injection improves the skin conditionand/or appearance. For example, improving a skin appearance may include,but is not limited to, rehydrating the skin, providing increasedelasticity to the skin, reducing skin roughness, making the skin tauter,reducing or eliminating stretch lines or marks, giving the skin bettertone, shine, brightness and/or radiance to reduce paleness, reducing oreliminating wrinkles in the skin, and providing wrinkle resistance tothe skin.

As used herein, the term “dermal region” refers to the region of skincomprising the epidermal-dermal junction and the dermis, including thesuperficial dermis (papillary region) and the deep dermis (reticularregion). The skin is composed of three primary layers: the epidermis,which provides waterproofing and serves as a barrier to infection; thedermis, which serves as a location for the appendages of skin; and thehypodermis (subcutaneous adipose layer). The epidermis contains no bloodvessels, and is nourished by diffusion from the dermis. The main type ofcells which make up the epidermis include, but are not limited to,keratinocytes, melanocytes, Langerhans cells and Merkels cells.

The dermis is the layer of skin beneath the epidermis that consists ofconnective tissue and cushions the body from stress and strain. Thedermis is tightly connected to the epidermis by a basement membrane. Italso harbors many mechanoreceptor/nerve endings that provide the senseof touch and heat. It contains the hair follicles, sweat glands,sebaceous glands, apocrine glands, lymphatic vessels and blood vessels.The blood vessels in the dermis provide nourishment and waste removalfrom its own cells as well as from the Stratum basale of the epidermis.The dermis is structurally divided into two areas: a superficial areaadjacent to the epidermis, called the papillary region, and a deepthicker area known as the reticular region.

The papillary region is composed of loose areolar connective tissue. Itis named for its fingerlike projections called papillae that extendtoward the epidermis. The papillae provide the dermis with a “bumpy”surface that interdigitates with the epidermis, strengthening theconnection between the two layers of skin. The reticular region liesdeep in the papillary region and is usually much thicker. It is composedof dense irregular connective tissue, and receives its name from thedense concentration of collagenous, elastic, and reticular fibers thatweave throughout it. These protein fibers give the dermis its propertiesof strength, extensibility, and elasticity. Also located within thereticular region are the roots of the hair, sebaceous glands, sweatglands, receptors, nails, and blood vessels. Stretch marks frompregnancy are also located in the dermis.

The hypodermis is not part of the skin, and lies below the dermis. Itspurpose is to attach the skin to underlying bone and muscle as well assupplying it with blood vessels and nerves. It consists of looseconnective tissue and elastin. The main cell types are fibroblasts,macrophages and adipocytes (the hypodermis contains 50% of body fat).Fat serves as padding and insulation for the body.

In one set of embodiments, methods of treatment are provided. In oneembodiment, a method of treating a lack of skin elasticity comprisesinjecting to a dermal region suffering from a lack of skin elasticityany embodiment of the compositions or injectable compositions describedherein, wherein the injection of the composition increases theelasticity of the skin, thereby treating a lack of skin elasticity.

In another embodiment, a method of treating skin roughness comprisesinjecting to a dermal region suffering from skin roughness anyembodiment of the compositions or injectable compositions describedherein, wherein the injection of the composition decreases skinroughness, thereby treating skin roughness.

In still another embodiment, a method of treating a lack of skintautness comprises injecting to a dermal region suffering from a lack ofskin tautness any embodiment of the compositions or injectablecompositions described herein, wherein the injection of the compositionmakes the skin tauter, thereby treating a lack of skin tautness.

In a further embodiment, a method of treating a skin stretch line ormark comprises injecting to a dermal region suffering from a skinstretch line or mark any embodiment of the compositions or injectablecompositions described herein, wherein the injection of the compositionreduces or eliminates the skin stretch line or mark, thereby treating askin stretch line or mark.

In another embodiment, a method of treating skin wrinkles comprisesinjecting to a dermal region suffering from skin wrinkles any embodimentof the compositions or injectable compositions described herein, whereinthe injection of the composition reduces or eliminates skin wrinkles,thereby treating skin wrinkles.

In yet another embodiment, a method of treating, preventing or delayingthe formation of skin wrinkles comprises injecting to a dermal regionsusceptible to, or showing signs of wrinkles any embodiment of thecompositions or injectable compositions described herein, wherein theinjection of the composition makes the skin resistant to skin wrinkles,thereby treating, preventing or delaying the formation of skin wrinkles.

In some embodiments of the methods and/or compositions and/or injectablecompositions described herein, the compositions and/or injectablecompositions can be used to treat a target site (e.g., a target site ofno more than 3 cm³, no more than 2 cm³, or no more than 1 cm³) forurogenital applications (e.g., a target site, e.g., a defect, in abladder tissue). For example, urethral bulking—where bulking material isinjected into the bladder neck and urethra—is used to treat incontinencedue to sphincter deficiency. In some embodiments, the compositionsand/or injectable compositions described herein can bulk urethra walls,restoring the sealing mechanism, and be programmed for long term volumeretention for lasting effect. For example, the silk fibroin particlescan maintain up to about 90%, or up to about 85%, or up to about 80%, orup to about 75%, or up to about 70%, or up to about 60%, or up to about50%, of the particles' original volume (e.g., injected volume) for atleast about 3 months or longer (including, e.g., at least about 4months, at least about 5 months, at least about 6 months, at least about7 months, at least about 8 months, at least about 9 months, at leastabout 10 months, at least about 11 months, at least about 12 months orlonger) after injection (e.g., up to about 24 months after injection).In some embodiments, the silk fibroin particles can maintain at leastabout 20%, at least about 30%, at least about 40%, at least about 50%,at least about 60%, at least about 70%, at least about 80%, or at leastabout 90%, of the particles' original volume (e.g., injected volume) forat least about 3 months or longer (including, e.g., at least about 4months, at least about 5 months, at least about 6 months, at least about7 months, at least about 8 months, at least about 9 months, at leastabout 10 months, at least about 11 months, at least about 12 months orlonger) after injection (e.g., up to about 36 months after injection).Combinations of the above-referenced ranges are also possible. Forexample, in some embodiments, the silk fibroin particles can maintainabout 20% to about 90% or about 30% to about 80%, or about 40% to about70% of the particles' original volume (e.g., injected volume) for atleast about 3 months or longer (including, e.g., at least about 4months, at least about 5 months, at least about 6 months, at least about7 months, at least about 8 months, at least about 9 months, at leastabout 10 months, at least about 11 months, at least about 12 months orlonger) after the injection (e.g., up to about 36 months afterinjection).

In some embodiments of the methods and/or compositions and/or injectablecompositions described herein, the compositions and/or injectablecompositions can be used to treat cervical insufficiency, a diseasewhich is known to increase the risk of preterm labor. An injectablebulking agent into the walls of cervix can enhance the mechanicalproperties of the cervical canal to reduce the risk of early pregnancy.Current treatments for cervical insufficiency include cervical cerclage,which is often associated with hemorrhage, tearing, and difficultimplantation procedures. A minimally invasive injectable alternativeusing compositions and/or injectable compositions described herein mayimprove tissue mechanics without the drawbacks associated with sutures.In some embodiments, the compositions and/or injectable compositionsdescribed herein can bulk the walls of cervix to reduce the risk ofearly pregnancy.

In some embodiments of the methods and/or compositions and/or injectablecompositions described herein, the compositions and/or injectablecompositions can be used to augment vocal fold in subjects in needthereof, e.g., a subject having vocal cord paresis, paralysis or glotticinsufficiency. In these embodiments, the method comprises injecting to atarget site (e.g., a glottal gap) in the vocal fold a subject in needthereof any embodiment of the compositions or injectable compositionsdescribed herein, with a 18-30 gauge needle (e.g., 18, 19, 20, 21, 22,23, 24, 25, 26, 27, 28, 29, 30) such that a standard deviation ofextrusion force of the composition through a 18-30 (e.g., 18, 19, 20,21, 22, 23, 24, 25, 26, 27, 28, 29, or 30) gauge needle, as determinedbetween about 50% extrusion volume and about 90% extrusion volume, isless than about 40%, less than about 35%, less than about 30%, less thanabout 25%, less than about 20%, less than about 15%, less than about10%, less than about 5%, or less than about 1%, of an average extrusionforce for the corresponding range of the extrusion volume (i.e., about50%-about 90% extrusion volume). In some embodiments, the standarddeviation of extrusion force of the composition through a 18-30 (e.g.,18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30) gauge needle, asdetermined between about 50% extrusion volume and about 90% extrusionvolume, is at least about 0.1%, at least about 0.5%, at least about 1%,at least about 5%, at least about 10%, at least about 15%, or at leastabout 20%, of an average extrusion force for the corresponding range ofthe extrusion volume (i.e., about 50%-about 90% extrusion volume).Combinations of the above-referenced ranges are also possible. Forexample, in some embodiments, the standard deviation of extrusion forceof the composition through a 18-30 (e.g., 18, 19, 20, 21, 22, 23, 24,25, 26, 27, 28, 29, or 30) gauge needle, as determined between about 50%extrusion volume and about 90% extrusion volume, is about 0.1% to about40%, or about 1% to about 20%, or about 1% to about 15%, of an averageextrusion force for the corresponding range of the extrusion volume(i.e., about 50%-about 90% extrusion volume).

In some embodiments, the method comprises injecting to a target site(e.g., a glottal gap) in the vocal fold of a subject in need thereof anyembodiment of the compositions or injectable compositions describedherein, with a 18-30 gauge needle (e.g., 18, 19, 20, 21, 22, 23, 24, 25,26, 27, 28, 29, or 30) using an average extrusion force of no more than60 N, e.g., no more than 55 N, no more than 50 N, no more than 45 N, nomore than 40 N, no more than 35 N, no more than 30 N, no more than 25 N,no more than 20 N, no more than 15 N, no more than 10 N, or no more than5 N. In some embodiments, the average extrusion force can be at leastabout 5 N, at least about 6 N, at least about 7 N, at least about 8 N,at least about 9 N, at least about 10 N, at least about 15 N, at leastabout 20 N, at least about 25 N, at least about 30 N, at least about 40N, at least about 50 N, or at least about 60 N. Combinations of theabove-referenced ranges are also possible. In some embodiments, theaverage extrusion force can range from 5 N to about 60 N, from about 10N to about 60 N, or from about 5N to about 30N, or from about 5N toabout 25N, or about 5 N to about 20 N, or about 5N to about 15N, orabout 5N to about 10 N. In some embodiments, the injection can comprisetrans-oral injection, trans-nasal injection, percutaneous injection, orthyroid injection. In some embodiments, the injection is trans-oral ortrans-nasal injection, for example, which can be performed with theinjection tube described herein for coupling to a laryngoscope or otherendoscope and delivering the composition to the site of defect in thevocal fold.

In some embodiments involving the methods for augmenting a vocal fold,the composition and/or injectable composition can comprise (i) silkfibroin particles and (ii) a carrier comprising any one or more examplesof a glycosaminoglycan polymer, an extracellular matrix, apolysaccharide, or a fibrous protein polymer described herein. Forexample, in one embodiment, the composition comprises silk fibroinparticles and a hyaluronic acid carrier (crosslinked and/ornon-crosslinked). In some embodiments, the silk fibroin particles havean average particle size in one or more ranges described herein, e.g.,about 300 μm to about 450 μm, or about 200 μm to about 500 μm. In someembodiments, the hyaluronic acid (HA) in the composition for augmentingvocal fold has a molecular weight range of about 750 kDa to about 1000kDa (with a weighted average of about 800 kDa to about 850 kDa, e.g.,about 823 kDa), and a crosslink density of about 4 mol % to about 15 mol% (e.g., 13 mol %), wherein the crosslink density is computed as thetotal number of molecules (or moles) of a crosslinking agent (e.g.,BDDE) incorporated into the crosslinked carrier (e.g., crosslinked HA)to the total number of repeating entity molecules (or moles) (e.g.,diasaccharides repeats) of the carrier (e.g., HA) present in thecrosslinked carrier (e.g., crosslinked HA), multiplied by 100.

In some embodiments, the composition and/or injectable composition foraugmenting a vocal fold can comprise a crosslinked matrix carrier (e.g.,as described herein) and porous silk fibroin particles (e.g., asdescribed herein), wherein the composition is characterized in that: (i)the crosslinked matrix carrier has a crosslink density of about 4 mol %to about 30 mol % (including the ranges described herein); (ii) theporous silk fibroin particles and the crosslinked matrix carrier arepresent in a volume ratio of about 5:95 to about 95:5 (including theranges described herein); and (iii) an average force of extruding about1 mL of the composition through a 18G-30G needle into air is less than60 N (including, e.g., less than 50 N, less than 40 N, or less than 30N, or the ranges described herein). The porous silk fibroin particlesprovide bulking effect to the vocal fold by maintaining up to 80% (e.g.,about 10% to about 80% or about 20% to about 80%, or about 30% to about70%) of the particles' original volume for at least 3 months or longer(including, e.g., at least 6 months, at least 9 months or longer) afterthe injection. The crosslinked matrix carrier may comprise crosslinkedglycosaminoglycan polymers (e.g., crosslinked hyaluronic acid),crosslinked extracellular matrix protein polymers (e.g., crosslinkedcollagen, crosslinked elastin, and/or crosslinked fibronectin),crosslinked polysaccharides (e.g., crosslinked cellulose), crosslinkedfibrous protein polymers, and a combination of two or more thereof. Insome embodiments, the crosslinked matrix carrier (e.g., crosslinkedhyaluronic acid) has a concentration of about 0.1% w/v to 10% w/v,including the ranges described herein.

In some embodiments, the composition and/or injectable composition foraugmenting a vocal fold is characterized in that the stiffness of thecomposition is decreased by at least about 15%, at least about 20%, atleast about 30%, at least about 40%, at least about 50%, at least about60%, at least about 70%, at least about 80%, at least about 90%, orhigher, as measured between about 0.1% strain and about 1% strain, orbetween about 0.1% strain and about 10% strain, or between about 0.1%strain and about 100% strain, or between about 10% strain and about 90%strain. In some embodiments, the stiffness of the composition isdecreased by no more than about 95%, no more than about 90%, no morethan about 80%, no more than about 70%, no more than about 60%, no morethan about 50%, no more than about 40%, no more than about 30%, or nomore than about 20%, as measured between about 0.1% strain and about 1%strain, or between about 0.1% strain and about 10% strain, or betweenabout 0.1% strain and about 100% strain, or between about 10% strain andabout 90% strain. Combinations of the above-referenced ranges are alsopossible. In some embodiments, the stiffness of the composition isdecreased by about 10% to about 90% or about 15% to about 80%, or about10% to about 40% or about 10% to about 30%, as measured between about0.1% strain and about 1% strain, or between about 0.1% strain and about10% strain, or between about 0.1% strain and about 100% strain, orbetween about 10% strain and about 90% strain.

Any porous silk fibroin particles described herein can be used for themethods for vocal fold augmentation described herein. In someembodiments, the porous silk fibroin particles can comprise aplasticizer, examples of which include, but are not limited to analcohol, a sugar, and/or a polyol (e.g., glycerol) including otherexamples of plasticizers described herein. In some embodiments, theporous silk fibroin particles have an average particle size of about 200μm to about 500 μm, or about 300 μm to 450 μm. In some embodiments, theporous silk fibroin particles have a porous structure characterized byinterconnected pores having an average pore size of about 20 μm to about100 μm (including the ranges described herein). In some embodiments, theporous silk fibroin particles have an average porosity of at least 90%(e.g., about 90% to about 99%, or about 90% to about 98%). In someembodiments, the porous silk fibroin particles and the crosslinkedmatrix carrier are present in a volume ratio of about 30:70 to about70:30 or about 30:70 to about 50:50. Other volume ratios as describedherein are also possible.

In some embodiments of any methods for augmenting vocal fold describedherein, the silk fibroin particles provide a bulking effect such that itcloses the glottal gap by maintaining up to about 90%, or up to about85%, or up to about 80%, or up to about 75%, or up to about 70%, or upto about 60%, or up to about 50%, of the particles' original volume(e.g., injected volume) for at least about 3 months or longer(including, e.g., at least about 4 months, at least about 5 months, atleast about 6 months, at least about 7 months, at least about 8 months,at least about 9 months, at least about 10 months, at least about 11months, at least about 12 months or longer) after injection (e.g., up toabout 24 months after injection). In some embodiments, the silk fibroinparticles can maintain at least about 20%, at least about 30%, at leastabout 40%, at least about 50%, at least about 60%, at least about 70%,at least about 80%, or at least about 90%, of the particles' originalvolume (e.g., injected volume) for at least about 3 months or longer(including, e.g., at least about 4 months, at least about 5 months, atleast about 6 months, at least about 7 months, at least about 8 months,at least about 9 months, at least about 10 months, at least about 11months, at least about 12 months or longer) after injection (e.g., up toabout 36 months after injection). Combinations of the above-referencedranges are also possible. For example, in some embodiments, the silkfibroin particles can maintain about 20% to about 90% or about 30% toabout 80%, or about 40% to about 70% of the particles' original volume(e.g., injected volume) for at least about 3 months or longer(including, e.g., at least about 4 months, at least about 5 months, atleast about 6 months, at least about 7 months, at least about 8 months,at least about 9 months, at least about 10 months, at least about 11months, at least about 12 months or longer) after the injection (e.g.,up to about 36 months after injection).

In another aspect, any embodiment of the methods, compositions, and/orinjectable compositions described herein can be used for applications,including, e.g., fistula occlusion or similar wounds caused by injury orsurgery. For example, any embodiment of the compositions and/orinjectable compositions described herein can be used to seal theabnormal connection between two or more tissues, allowing epithelium todevelop around the silk implant, reforming a natural epithelial barrierand preventing the exchange of substances that may cause furtherinfection or inflammation.

In some embodiments, any embodiment of the compositions, and/orinjectable compositions described herein can be used as scaffolds tosupport cell growth for tissue engineering. For example, any embodimentof the compositions, and/or injectable compositions described herein canbe administered into an incision or wound site to promote wound healingor wound disclosure. The methods generally comprise administering anyembodiment of the compositions, and/or injectable compositions describedherein, at the wound or incision site and allowing the wound or incisionto heal while the silk fibroin particles is eroded or absorbed in thebody and is replaced with the individual's own viable tissue. Themethods can further comprise seeding the silk fibroin particles ormixing the composition with viable cellular material, either from theindividual or from a donor, prior to or during administration.

For any methods of use described herein, the effective amount andadministration schedule of any embodiment of the compositions and/orinjectable compositions described herein injected into a soft tissue(e.g., a dermal tissue, a bladder tissue, a cervical tissue, or a vocalfold tissue) can be determined by a person of ordinary skill in the arttaking into account various factors, including, without limitation, thesize, condition, and/or location of a defect to be treated, and theduration of treatment desired, the properties (e.g., degradation rate,and/or pharmacodynamics) of selected compositions and/or injectablecompositions for treatment, history and risk factors of the individual,such as, e.g., age, weight, general health, and any combinationsthereof. In some embodiments, any embodiment of the compositions and/orinjectable compositions described herein can be injected into a defectto be treated every about 3 months, every about 6 months, every about 9months, every about one year, every about two years or longer.

In some embodiments of any methods, compositions, and/or injectablecompositions described herein, the compositions or injectablecompositions comprising at least one active agent can be used as aplatform for drug delivery. For example, the silk fibroin particles canbe formed with a pharmaceutical agent either entrained in or bound tothe particles and then administered into the body (e.g., injection,implantation or even oral administration). In some embodiments, anactive agent can be mixed with silk fibroin particles and/or injectablecompositions and then administered into the body (e.g., injection,implantation or even oral administration). For extended or sustainedrelease, silk fibroin particles can manipulated, e.g., to modulate itsbeta-sheet content, for its volume retention and/or degradation rate.The therapeutic-bound silk fibroin particles can also be furthercrosslinked to enhance the stability to extend the release period. In analternative approach, silk fibroin particles can be mixed with otherpolymers, for examples, hyaluronic acid, to prolong the release ofcertain growth factors or cytokines and to stabilize the functionality.

As used herein, the term “sustained release” refers to the release of apharmaceutically-active drug over a period of about seven days or more.In aspects of this embodiment, a drug delivery platform comprising anyembodiment of the compositions or injectable compositions describedherein releases a pharmaceutically-active drug over a period of, e.g.,at least about 7 days after administration, at least about 15 days afteradministration, at least about 30 days after administration, at leastabout 45 days after administration, at least about 60 days afteradministration, at least about 75 days after administration, or at leastabout 90 days after administration (and/or up to 360 days or up to 120days after administration).

As used herein, the term “extended release” refers to the release of apharmaceutically-active drug over a period of time of less than aboutseven days. In such embodiments, a drug delivery platform comprising anyembodiment of the compositions or injectable compositions describedherein can release a pharmaceutically-active drug over a period of,e.g., about 1 day after administration, about 2 days afteradministration, about 3 days after administration, about 4 days afteradministration, about 5 days after administration, or about 6 days afteradministration.

Depending on the formulation and processing methods of the compositionsand the associated applications, any embodiment of the compositions orinjectable compositions described herein can be administered (e.g., byinjection) periodically, for example, every about 3 months, every about4 months, every about 5 months, every about 6 months, every about 7months, every about 8 months, every about 9 months, every about 10months, every about 11 months, every about 1 year, every about 2 yearsor longer.

In some embodiments of any of the applications described herein, anyembodiment of the compositions or injectable compositions describedherein can be injected subcutaneously, submuscularly, orintramuscularly. In some embodiments, the methods and/or compositionsdescribed herein can be used in the dermal region. In some embodiments,the methods and/or compositions described herein can be used in theepidermal layer, dermal layer, hypodermis layer, or any combinationsthereof.

Exemplary Methods of Making the Compositions Described Herein

Silk fibroin particles are mixed with or suspended in at least onecarrier as described herein in an appropriate volume ratio to form thecompositions described herein. In some embodiments, the carrier (e.g.,first carrier, second carrier) can be crosslinked, e.g., prior to mixingwith the silk fibroin particles. For example, hyaluronic acid as acarrier can be chemically crosslinked using a crosslinking agent, priorto mixing with silk fibroin particles to form the compositions describedherein. Examples of crosslinking agents that can be used to chemicallycrosslink hyaluronic acid include, but are not limited to divinylsulfone, diepoxyoctane, epoxypropoxy butane, epoxypropoxy ethylene, and1,4-butanediol-diglycidylether.

Silk fibroin particles can be modified through controlled partialremoval of silk sericin or deliberate enrichment of source silk withsericin. This can be accomplished by varying the conditions, such astime, temperature, concentration, and the like for the silk degummingprocess.

Degummed silk can be prepared by any conventional method known to oneskilled in the art. For example, B. mori cocoons are boiled for a periodof pre-determined time in an aqueous solution. Generally, a longdegumming time generates low molecular silk fibroin fragments. See WO2014/145002 for methods of making low molecular weight silk fibroinfragments, the content of which is incorporated herein by reference inits entirety. In some embodiments, the silk cocoons are boiled for atleast about 10 minutes, at least about 20 minutes, at least about 30minutes, at least about 40 minutes, at least about 50 minutes, at leastabout 60 minutes, at least about 70 minutes, at least about 80 minutes,at least about 90 minutes, at least about 100 minutes, at least about110 minutes, at least about 120 minutes, or longer (e.g., up to about180 minutes). In some embodiments, the silk cocoons may be boiled for nomore than about 180 minutes, no more than about 170 minutes, no morethan about 160 minutes, no more than about 150 minutes, no more thanabout 140 minutes, no more than about 130 minutes, no more than about120 minutes, no more than about 110 minutes, no more than about 100minutes, no more than about 90 minutes, no more than about 80 minutes,no more than about 70 minutes, no more than about 60 minutes, no morethan about 50 minutes, no more than about 40 minutes, no more than about30 minutes, no more than about 20 minutes, no more than about 10minutes. Combinations of the above-referenced ranges are also possible.For example, in some embodiments, the silk cocoons may be boiled forabout 10 minutes to about 180 minutes, about 15 minutes to about 160minutes, about 20 minutes to about 140 minutes, or about 30 minutes toabout 120 minutes. In some embodiments, silk cocoons can be heated orboiled at an elevated temperature (e.g., for an amount of time describedabove). For example, in some embodiments, silk cocoons may be heated orboiled at a temperature of at least about 95° C., at least about 100°C., at least about 101.0° C., at least about 101.5° C., at least about102.0° C., at least about 102.5° C., at least about 103.0° C., at leastabout 103.5° C., at least about 104.0° C., at least about 104.5° C., atleast about 105.0° C., at least about 105.5° C., at least about 106.0°C., at least about 106.5° C., at least about 107.0° C., at least about107.5° C., at least about 108.0° C., at least about 108.5° C., at leastabout 109.0° C., at least about 109.5° C., at least about 110.0° C., atleast about 110.5° C., at least about 111.0° C., at least about 111.5°C., at least about 112.0° C., at least about 112.5° C., at least about113.0° C., at least about 113.5° C., at least about 114.0° C., at leastabout 114.5° C., at least about 115.0° C., at least about 115.5° C., atleast about 116.0° C., at least about 116.5° C., at least about 117.0°C., at least about 117.5° C., at least about 118.0° C., at least about118.5° C., at least about 119.0° C., at least about 119.5° C., at leastabout 120.0° C., or higher (e.g., up to about 130° C.). In someembodiments, silk cocoons may be heated or boiled a temperature of nomore than about 130° C., no more than about 125° C., no more than about120° C., no more than about 105° C., or no more than about 100° C.Combinations of the above-referenced ranges are also possible. In someembodiments, silk cocoons may be heated or boiled at a temperature ofabout 95° C. to about 110° C., or about 100° C. to about 105° C.

In some embodiments, the elevated temperature at any of theabove-referenced ranges can be achieved by carrying out at least portionof the heating process (e.g., boiling process) under suitable pressure.For example, the suitable pressure under which silk fibroin fragmentsare produced are typically between about 10-40 psi, between about 10-35psi, between about 10-30 psi, or between about 10-20 psi. In someembodiments, the pressure may be at least about 10 psi, at least about11 psi, at least about 12 psi, at least about 13 psi, at least about 14psi, at least about 15 psi, at least about 20 psi, at least about 25psi, at least about 30 psi, at least about 35 psi, or at least about 40psi. In some embodiments, the pressure may be no more than 40 psi, nomore than 35 psi, no more than 30 psi, no more than 25 psi, no more than20 psi, no more than 15 psi, or no more than 10 psi. Combinations of theabove-referenced ranges are also possible.

In one embodiment, the aqueous solution used in the process of degummingsilk cocoons is about 0.001 M to about 0.5 M Na₂CO₃ (e.g., about 0.02 MNa₂CO₃ in one embodiment). The cocoons are rinsed, for example, withwater to extract the sericin proteins. The degummed silk can be thendissolved, e.g., in an aqueous salt solution. Salts useful for thispurpose include lithium bromide, lithium thiocyanate, calcium nitrate orother chemicals capable of solubilizing silk. In some embodiments, thedegummed silk can be dissolved by maintaining the silk fibers in about8M-12 M LiBr solution, or in about 8.5M-11.5M LiBr solution, or in about9M-11M LiBr solution for up to 6 hours (including, e.g., up to 5 hours,up to 4 hours, up to 3 hours, up to 2 hours, up to 1 hr) at an averagetemperature of about 55° C. to about 65° C. In some embodiments, theaverage temperature is about 60° C. The salt is consequently removedusing, for example, dialysis. In most cases dialysis for about 2-12hours can be sufficient. However, in some embodiments, dialysis can beperformed for more than about 12 hours, e.g., at least about 12 hours,at least about 24 hours, at least about 2 days, at least about 3 days,at least about 4 days, at least about 5 days or longer (e.g., up toabout 1 week). See, for example, International Patent ApplicationPublication Number. WO 2005/012606, the content of which is incorporatedherein by reference in its entirety.

If necessary, the solution can then be concentrated using, for example,dialysis against a hygroscopic polymer, for example, PEG, a polyethyleneoxide, or amylose. In some embodiments, the PEG is of a molecular weightof 8,000-10,000 g/mol and has a concentration of about 10% to about 50%(w/v). A slide-a-lyzer dialysis cassette (Pierce, MW CO 3500) can beused. However, any suitable dialysis system can be used. The dialysiscan be performed for a time period sufficient to result in a finalconcentration of aqueous silk solution between about 10% to about 30%.In most cases dialysis for about 2-12 hours can be sufficient. See, forexample, International Patent Application Publication Number. WO2005/012606, the content of which is incorporated herein by reference inits entirety.

In some embodiments, the silk fibroin solution can be purified, e.g., bycentrifugation or filtration, e.g., using a 0.2 μm filter.

Silk fibroin particles can be produced from aqueous-based or organicsolvent-based silk fibroin solutions. In some embodiments, silk fibroinparticles produced from organic solvent-based silk fibroin solution(e.g., silk fibroin dissolved in hexafluoroisopropanol (HFIP), see, forexample, International Application No. WO2004/000915, content of whichis incorporated herein by reference in its entirety) can maintain theparticles' original volume for a longer period of time (or degrade at aslower rate) than that of aqueous-based silk fibroin particles. Theaqueous- or organic solvent-based silk fibroin solution used for makingsilk fibroin particles described herein can be prepared using anytechniques known in the art.

The concentration of silk fibroin in solutions can be suited to aparticular volume retention or degradation requirement. For example,higher concentrations of silk fibroin solutions can be used when longervolume retention or slower degradation rate of the silk fibroinparticles is desired upon injection into a tissue to be repaired oraugmented. In some embodiments, the silk fibroin solution for making thesilk fibroin particles described herein can vary from about 4% (w/v) toabout 30% (w/v), inclusive, or about 4% (w/v) to about 20% (w/v),inclusive. In some embodiments, the silk fibroin solution can vary fromabout 6% (w/v) to about 20% (w/v). In some embodiments, the silk fibroinsolution can vary from about 6% (w/v) to about 17% (w/v). Suitableprocesses for preparing silk fibroin solution are disclosed, forexample, in U.S. Pat. No. 7,635,755; and International ApplicationNumbers: WO/2005/012606; and WO/2008/127401. A micro-filtration step canbe used herein. For example, the prepared silk fibroin solution can beprocessed further, e.g., by centrifugation and/or syringe basedmicro-filtration before further processing into silk fibroin particlesdescribed herein.

In some embodiments, one or more biocompatible and/or biodegradablepolymers (e.g., two or more biocompatible polymers) including the onesdescribed herein, can be added to the silk fibroin solution to form silkfibroin particles. In some embodiments, one or more polymericplasticizers, carriers, and/or protein additives that enhance cellularresponse, immune response, and/or regeneration/tissue regrowth, can beadded to the silk fibroin solution to form silk fibroin particles.

In some embodiments, at least one active agent described herein can beadded to the silk fibroin solution before further processing into silkfibroin particles described herein. In some embodiments, the activeagent can be dispersed homogeneously or heterogeneously within the silkfibroin, dispersed in a gradient, e.g., using the carbodiimide-mediatedmodification method described in the U.S. Patent Application No. US2007/0212730. In some embodiments, the silk fibroin particles can befirst formed and then contacted with (e.g., dipped into) at least oneactive agent such that the open surface of the particles can be coatedwith at least one active agent.

The silk fibroin particles can be produced by any methods known in theart. In some embodiments, the silk fibroin particles can be reduced froma solid-state silk fibroin matrix by a mechanical means. Exemplarymechanical means to obtain silk fibroin particles include micronizing,milling, pulverizing, crushing, grinding, freeze-drying or anycombination thereof. Methods of forming a solid-state silk fibroin froma silk fibroin solution may involve, e.g., using a solvent-based or anaqueous-based silk fibroin solution. See, e.g., Wang Y. et al. (2008) 29Biomaterials 3415, U.S. Pat. No. 7,635,755; and InternationalApplication Nos: WO/2005/012606; and WO/2008/127401.

In some embodiments, the silk fibroin particles are derived from a bulksilk fibroin sponge produced according to one embodiment of the methoddescribed in the International Patent Publication No. WO 2016/145281,the content of which is incorporated herein by reference in itsentirety. For example, as described in Example 1, a concentrated silkfibroin solution (e.g., 8-12% w/v) mixed with a plasticizer (e.g.,glycerol) at a concentration of about 3-30% w/w (including, e.g., about3-20% w/w or about 3-10% w/w) is prepared and then frozen at a freezingtemperature of about −30° C. to about −10° C. in a lyophilizer undercontrolled slow freezing rate (about −0.1° C./min to about −0.01°C./min), followed by vacuum at about 50 mTorr to about 200 mTorr forabout 36 hours to about 100 hours, to produce a sponge-like material.The bulk silk fibroin sponge can then be reduced to particles (e.g.,round particles) using any mechanical means, e.g., grinding, milling,and cutting. In some embodiments, particles of a desired size range canbe separated from others, e.g., by sieving.

In some embodiments, the silk fibroin particles can be lyophilized priorto mixing with a carrier as described herein.

Methods for generating porous structures within silk fibroin matrix,e.g., freeze-drying, salt-leaching, and gas foaming methods, may beused, as described in, e.g., U.S. Pat. No. 7,842,780; and US PatentApplication Nos: US 2010/0279112; and US 2010/0279112, the contents ofwhich are incorporated herein by reference in their entirety.

In some embodiments, silk fibroin particles or a solid-state silkfibroin described herein can be subjected to a post-treatment that willaffect at least one silk fibroin property. For example, post-treatmentof silk fibroin particles or a solid-state silk fibroin can affect silkfibroin properties including β-sheet content, solubility, active agentloading capacity, degradation time, drug permeability, or anycombinations thereof. Silk post-processing options include controlledslow drying (Lu et al., 10 Biomacromolecules 1032 (2009)), waterannealing (Jin et al., Water—Stable Silk Films with Reduced β-SheetContent, 15 Adv. Funct. Mats. 1241 (2005)), stretching (Demura &Asakura, Immobilization of glucose oxidase with Bombyx mori silk fibroinby only stretching treatment and its application to glucose sensor, 33Biotech & Bioengin. 598 (1989)), compression, and solvent immersion,including methanol (Hofmann et al., 2006), ethanol (Miyairi et al.,1978), glutaraldehyde (Acharya et al., 2008) and N-ethyl-N′-(3-dimethylaminopropyl) carbodiimide (EDC) (Bayraktar et al., 2005).

In some embodiments, post-treatment of the solid-state silk fibroin orsilk fibroin particles, e.g., water—annealing or solvent immersion, canmodulate the degradation or solubility properties of the silk fibroinparticles described herein. In some embodiments, post-treatment of thesolid-state silk fibroin or silk fibroin particles, e.g.,water-annealing or solvent immersion, can modulate the volume retentionproperties of the silk fibroin particles described herein.

In some embodiments, the silk fibroin particles described herein can becoated with at least one layer of a biocompatible and/or biodegradablepolymer described herein, e.g., to modulate the degradation and/orvolume retention properties of the silk fibroin particles upon injectioninto a tissue to be treated and/or to modulate the rate of activeagents, if any, released from the silk fibroin particles. In suchembodiments, the biocompatible and/or biodegradable polymer can compriseat least one active agent.

In some embodiments, the silk fibroin particles described herein can becoated with cell adhesion molecules, e.g., but not limited to,fibronectin, vitronectin, laminin, collagen, any art-recognizedextracellular matrix molecules, and any combinations thereof.

In some embodiments, the silk fibroin particles described herein can besterilized. In some embodiments, compositions comprising silk fibroinparticles and a matrix carrier (e.g., but not limited to HA) aresterilized. In some embodiments, a delivery device (e.g., but notlimited to a syringe) comprising silk fibroin particles and a matrixcarrier (e.g., but not limited to HA) are sterilized. Sterilizationmethods for biomaterials and/or biomedical devices are well known in theart, including, but not limited to, gamma or ultraviolet radiation,autoclaving (e.g., heat/steam); alcohol sterilization (e.g., ethanol andmethanol); gas sterilization (e.g., ethylene oxide sterilization) andheat sterilization.

In some embodiments, compositions comprising silk fibroin particles anda matrix carrier (e.g., but not limited to HA) are subject to heatsterilization. In some embodiments, a delivery device (e.g., but notlimited to a syringe) comprising silk fibroin particles and a matrixcarrier (e.g., but not limited to HA) are subject to heat sterilization.

In some embodiments involving the silk fibroin particles and/orcompositions described herein, the silk fibroin particles and/orcompositions may be sterilized (e.g., heat sterilized) such that thesterility assurance level (SAL) is sufficiently low, e.g., to complywith the regulatory requirement. In some embodiments, the sterilizedsilk fibroin particles and/or compositions described herein has a SAL ofabout 10⁻⁶ or lower.

In some embodiments involving the silk fibroin particles and/orcompositions described herein, the silk fibroin solution used to makethe silk fibroin particles can be sterilized, e.g., by sterilefiltration, prior to forming silk fibroin particles from the silkfibroin solution.

Further, the silk fibroin particles described herein can take advantageof the many techniques developed to functionalize silk fibroin (e.g.,active agents such as dyes and sensors). See, e.g., U.S. Pat. No.6,287,340, Bioengineered anterior cruciate ligament; WO 2004/000915,Silk Biomaterials & Methods of Use Thereof; WO 2004/001103, SilkBiomaterials & Methods of Use Thereof; WO 2004/062697, Silk FibroinMaterials & Use Thereof; WO 2005/000483, Method for Forming inorganicCoatings; WO 2005/012606, Concentrated Aqueous Silk Fibroin Solution &Use Thereof; WO 2011/005381, Vortex-Induced Silk fibroin Gelation forEncapsulation & Delivery; WO 2005/123114, Silk-Based Drug DeliverySystem; WO 2006/076711, Fibrous Protein Fusions & Uses Thereof in theFormation of Advanced Organic/Inorganic Composite Materials; U.S.Application Pub. No. 2007/0212730, Covalently immobilized proteingradients in three-dimensional porous scaffolds; WO 2006/042287, Methodfor Producing Biomaterial Scaffolds; WO 2007/016524, Method for StepwiseDeposition of Silk Fibroin Coatings; WO 2008/085904, BiodegradableElectronic Devices; WO 2008/118133, Silk Microspheres for Encapsulation& Controlled Release; WO 2008/108838, Microfluidic Devices & Methods forFabricating Same; WO 2008/127404, Nanopatterned Biopolymer Device &Method of Manufacturing Same; WO 2008/118211, Biopolymer PhotonicCrystals & Method of Manufacturing Same; WO 2008/127402, BiopolymerSensor & Method of Manufacturing Same; WO 2008/127403, BiopolymerOptofluidic Device & Method of Manufacturing the Same; WO 2008/127401,Biopolymer Optical Wave Guide & Method of Manufacturing Same; WO2008/140562, Biopolymer Sensor & Method of Manufacturing Same; WO2008/127405, Microfluidic Device with Cylindrical MicroChannel & Methodfor Fabricating Same; WO 2008/106485, Tissue-Engineered Silk Organs; WO2008/140562, Electroactive Biopolymer Optical & Electro-Optical Devices& Method of Manufacturing Same; WO 2008/150861, Method for Silk FibroinGelation Using Sonication; WO 2007/103442, Biocompatible Scaffolds &Adipose-Derived Stem Cells; WO 2009/155397, Edible Holographic SilkProducts; WO 2009/100280, 3-Dimensional Silk HydroxyapatiteCompositions; WO 2009/061823, Fabrication of Silk Fibroin PhotonicStructures by Nanocontact Imprinting; WO 2009/126689, System & Methodfor Making Biomaterial Structures.

Although preferred embodiments have been depicted and described indetail herein, it will be apparent to those skilled in the relevant artthat various modifications, additions, substitutions, and the like canbe made without departing from the spirit of the invention and these aretherefore considered to be within the scope of the invention as definedin the claims which follow. Further, to the extent not alreadyindicated, it will be understood by those of ordinary skill in the artthat any one of the various embodiments herein described and illustratedmay be further modified to incorporate features shown in any of theother embodiments disclosed herein.

The disclosure is further illustrated by the following examples whichshould not be construed as limiting. The examples are illustrative only,and are not intended to limit, in any manner, any of the aspectsdescribed herein. The following examples do not in any way limit theinvention.

EXAMPLES Example 1: Fabrication of Silk Particles

FIG. 1 is a schematic representation of an exemplary method of makingsilk particles and compositions according to some embodiments describedherein. The silk fibroin particles are derived from a bulk silk fibroinsponge produced according to one embodiment of the method described inthe International Patent Publication No. WO 2016/145281, the content ofwhich is incorporated herein by reference in its entirety. Aconcentrated silk fibroin solution (e.g., 8-12% w/v) mixed with aplasticizer (e.g., glycerol) at a concentration of about 3-30% w/w(including, e.g., about 3-20% w/w or about 3-10% w/w) is prepared andthen frozen at a freezing temperature of about −30° C. to about −10° C.in a lyophilizer under controlled slow freezing rate (about −0.1° C./minto about −0.01° C./min), followed by vacuum at about 50 mTorr to about200 mTorr for about 36 hours to about 100 hours, to produce asponge-like material.

After lyophilization, the silk fibroin/plasticizer material is subjectedto solvent treatment, e.g., immersion in methanol for about 6-24 hours,and air drying for at least about 1 hour to form a bulk silk fibroinsponge. Formation of β-sheet structure in silk fibroin can be evaluatedvia Fourier Transform Infrared Spectroscopy (FTIR), which is wellestablished in the art. Measurement of β-sheet content is typicallyperformed by FTIR spectral deconvolution and peak fitting. This methodis a manipulation of the data, and meant to represent comparative data,rather than empirical values. In some embodiments, an increase inβ-sheet content by FTIR analysis from 20-30% β-sheet before methanol(MeOH) treatment, to approx. 45-55% β-sheet after MeOH treatment iscontemplated. This change would be enough to greatly reduce thesolubility of dried silk materials in aqueous media (e.g. PBS, H₂O), andextend in vivo volume retention.

The silk fibroin sponge is then subjected to mechanical grinding andsterilization to form silk fibroin particles according to one set ofembodiments described herein. FIG. 2 is a microscopic image ofindividual silk fibroin particles according to one set of embodimentsdescribed herein. The porous silk fibroin particle have an averageparticle size of about 500 microns to about 600 microns in diameter andan average pore size of about 40 μm in diameter. Such particle size canprovide mechanical support to a carrier for tissue bulking, e.g., toretain tissue volume over a specified duration, e.g., of one year orlonger. In addition, the porous, three-dimensional structure of the silkfibroin particles promotes cell attachment and migration, which in turnspromotes interactions with the surrounding matrix for cellproliferation. Additionally, the slow degradation rate of the particlesin vivo offers long-term scaffolding and support.

In some embodiments, silk fibroin particles of a desired size range canbe separated from other particles, e.g., by sieving. For example, FIG.51A shows a size distribution of silk fibroin particles produced by themethod described above and sieved to about 75 μm to about 125 μm, andFIG. 51B is a representative image of silk fibroin particles accordingto one set of embodiments described herein.

The concentration of silk fibroin in the silk fibroin particles is atleast about 95% w/v or higher, including, e.g., at least about 96% w/v,at least about 97% w/v, at least about 98% w/v, at least about 99% w/v,or up to 100% w/v. The resulting silk fibroin particles can then bemixed with a carrier (e.g., but not limited to hydrogel or autologousfat) in a desired ratio. For example, in one embodiment, the final silkconcentration relative to the carrier is about 40% (w/v).

FIGS. 5A-5C are scanning electron microscopic (SEM) images offreeze-dried silk fibroin materials with glycerol. As compared to thesilk fibroin material of FIG. 4B (without glycerol), which containedlarger non-porous crystals, which, without wishing to be bound bytheory, could be attributed to irregularities in freezing, the silkfibroin particles described herein had a more uniform size and containedmore evenly distributed, rounded pores. These results show that additionof a plasticizer, e.g., glycerol, can reduce or prevent inconsistent,non-homogenous freezing patterns.

Example 2: Delivery Device Hollow Needle

The hollow needle is fabricated from a 23XX gauge stainless steelhypotube with a frontside triple point cut as seen in FIGS. 24, 26A and26B. A wire cut electrical discharge machining (EDM) machine is used tofashion the lancet cut tip and form the needle. As seen in FIGS. 29, 30Aand 30B, the rear end of the needle is laser welded to a collar which isdesigned to prevent the needle from moving distally beyond thediameter-reduced portion of the outer sheath tube.

Example 3: Delivery Device Handle and Tubing

The handle is fabricated in two portions, a leading portion and a backportion. As seen in FIG. 34B, the back portion of the handle is designedto accommodate attachment of a Luer lock syringe. When the plunger onthe syringe is depressed, the material held within the syringe is pushedout of the syringe, through a hypotube, and into the inner tube. Thehandle includes an actuation mechanism that moves the needle between aretracted position where the needle is positioned within and covered bythe outer sheath tube and an extended position where the needle tip hasbeen moved outside the outer sheath tube and is exposed. The twoportions of the handle can move relative to one another, where oneportion of the handle can slide relative to the other portion. Slidingof one portion of the handle relative to the other moves the needlebetween the retracted and extended positions.

The handle is made from ABS plastic and is formed via injection molding.The inner tube and outer sheath tube is made from PTFE.

Example 4: Injection Delivery of the Silk Fibroin Particles According toOne Embodiment Described Herein

The silk particles produced by the method as described in Example 1 weremixed with a carrier (e.g., lipoaspirate, hyaluronic acid, polylacticacid, collagen, or combinations thereof) in a silk particle: carriervolume ratio of about 30:70 to about 50:50. When silk fibroin particleswere mixed with human fat, they conformed to the shape of a container,enabling more aesthetic sculpting of volume defect.

FIG. 6 shows subcutaneous delivery of a composition comprising silkfibroin particles according to one set of embodiments described hereinand a carrier to an animal for soft tissue augmentation. The top panelshows that a mouse was injected with control compositions andcompositions according to one set of embodiments described herein. Thebottom left panel shows a biopsy of the tissue site injected with amixture of silk fibroin particles and fat; and the bottom right panelshows a biopsy of the tissue site injected with control (fat alone).

Example 5: Air Extrusion Force of Exemplary Compositions Comprising SilkFibroin Particles and Lipoaspirate as a Carrier

An exemplary extrusion force method is described as follows: pre-loadedsyringes attached to a 14G or 16G needle are mounted vertically onto acustom syringe holder. A uniaxial mechanical tester (with a forcetransducer mounted to the top plate) depresses the plunger of thesyringe, extruding material through the needle and recording forcemeasurements via the attached transducer. The crosshead speed of the topplate is set to 5.5 mm/s (which extrudes 1 mL of material in 10 seconds)to achieve a constant rate of extrusion.

Samples of compositions (e.g., as described in Example 2) were extrudedinto air through a needle (e.g., 16G) of a syringe (e.g., with a volumeof 1 mL) at a selected crosshead speed (e.g., at 5.5 mm/s).

FIGS. 7A-7D are graphs showing extrusion forces resulting frominjections of lipoaspirate alone or in combination with silk fibroinparticles according to one set of embodiments described herein. FIG. 7A:force of extruding lipoaspirate alone through a 16G needle. FIG. 7B:force of extruding a mixture of 30% silk fibroin particles andlipoaspirate through a 16G needle. FIG. 7C: average extrusion forces ofindicated compositions using a 1 mL syringe, 14G needle system. FIG. 7D:average extrusion forces of indicated compositions using a 1 mL syringe,16G needle system. The compositions were extruded at a rate of 5.5 mm/sthrough 14G or 16G needles without clogging. Thus, in some embodiments,compositions comprising up to 40% volume of silk fibroin particles mixedwith lipoaspirate can be extruded through 1 mL syringe appended with a16G needle.

Example 6: Air Extrusion Force of Exemplary Compositions Comprising SilkFibroin Particles and Hyaluronic Acid (HA) as a Carrier

The HA at a concentration of 4% w/v was mixed with the silk particles ina volume ratio of 50:50. Extrusion forces of the composition weremeasured as described in Example 3. Samples were extruded through a 14Gor 16G, 1 mL syringe system, at a crosshead speed of 5.5 mm/s, whichwould inject 1 mL of material in 10 seconds.

FIGS. 8A-8D are graphs showing extrusion forces resulting frominjections of non-crosslinked hyaluronic acid (HA) alone or incombination with silk fibroin particles according to one set ofembodiments described herein. FIG. 8A: force of extruding HA alonethrough a 14G needle. FIG. 8B: force of extruding HA alone through a 16Gneedle. FIG. 8C: force of extruding a mixture of silk fibroin particlesand HA in a volume ratio of 50:50 through a 14G needle. FIG. 8D: forceof extruding a mixture of silk fibroin particles and HA in a volumeratio of 50:50 through a 16G needle. The silk fibroin particles wereextruded through 14G needles with no incidence of clogging. Thus, insome embodiments, compositions comprising up to 50% volume of silkfibroin particles mixed with non-crosslinked hyaluronic acid (e.g.,autoclaved hyaluronic acid) can be extruded through 1 mL syringeappended with a 14G needle.

Example 7: Exemplary Injectable Formulations for Soft Tissue RepairApplications

Scaffolds for soft tissue repair from Bombyx mori silk fibroin representa unique opportunity to provide both cosmetic and therapeutic functions,demonstrating bioresorbable features. Silk fibroin materials are knownto be used as cell scaffolds, and silk hydrogel and porous scaffoldformulations have been fabricated using porogens. Implantable silkmaterials have shown resorption properties, while also promoting cellin-growth. Silk fibroin scaffolds can also be reinforced withhexafluoroisopropanol (HFIP) or particles to provide additionalstrength.

There is a need to develop injectable formulations for soft tissuerepair applications, for example, comprising silk fibroin scaffold and acarrier such as lipoaspirate (fat). In one aspect, some embodimentsprovided herein relate to compositions comprising silk fibroin particlesthat uniformly have a volume mean diameter of about 500-600 um with a 44um mean pore size (FIGS. 9A-9B). In these embodiments, the silk fibroinparticles were produced as described below. A silk fibroin solution wasprepared as described in Rockwood et al. (Nature Protocols (2011) 6:1612-1631). Once generated, and diluted/concentrated to the desired wt %concentration, the silk fibroin solution was carefully lyophilized at−45° C. overnight to generate porous silk fibroin sponges with a 50-70um mean pore size. These silk fibroin sponges were then treated with analcohol (e.g., ethanol) to generate crosslinks within the silk proteinmatrix. The silk fibroin sponge was then mechanically ground to generateparticles of 500-600 um in diameter. Finally, the silk fibroin particleswere autoclaved and stored.

To prepare an injectable formulation comprising silk fibroin particlessuspended in a carrier such as lipoaspirate, in some embodiments, thesilk fibroin particles were mixed with fresh human fat, e.g., isolatedfrom liposuction to generate a silk fibroin particle/lipoaspiratemixture, which can have from 5-50% vol/vol silk particles dispersedwithin the lipoaspirate.

Unlike conventional silk fibroin particles, these silk fibroin particlesare unique in that they can be extruded easily from a small gauge needleat concentrations of 5-50% vol/vol in a carrier such as humanlipoaspirates. As seen in FIG. 9C, silk fibroin particles derived fromboth HFIP (as described in the International Patent Publication No.WO2013/071107) and aqueous processing (Rajkhowa et al. 2008) using anNaCl porogen leaching method were mixed with a 1.5% wt/vol silk hydrogelcarrier for injection force testing. These two existing silkformulations exhibit strong back-pressure and difficulty extrudingthrough a needle, resulting in frequent clogging events (injection forceregularly exceeding 100N) before full extrusion of the material. Bycontrast, the silk fibroin particles described herein can be extrudedfrom a 14 or 16 gauge needle (or larger gauge, e.g. 12G, 10G) at averageforces between 15-30N without clogging (FIG. 9D and Table 1), which aresuitable for clinical use in fat grafting applications.

TABLE 1 Average extrusion force of silk fibroin-lipoaspirateformulations Syringe Needle Extrusion Force (N) Formulation Size Gauge[Average ± STD] Lipoaspirate Only  1 mL 14 G 29.8 ± 8.0  30% v/v Silk  1mL 14 G 34.5 ± 17.0 Particles in Lipo 40% v/v Silk  1 mL 14 G 35.5 ±2.0  Particles in Lipo 16 G 28.4 ± 9.0  50% v/v Silk  1 mL 14 G 36.2 ±2.0  Particles in Lipo 16 G 50.4 ± 5.0  Lipoaspirate Only 20 mL 14 G19.8 ± 9.0  15% v/v Silk 20 mL 14 G 30.2 ± 15.0 Particles in LipoExtrusion forces reported as the average of N = 3

In some embodiments, the silk fibroin particles described herein can beextruded with lipoaspirate at concentrations from 10% v/v and greater(e.g., 15% v/v or greater) with relatively low extrusion force (withinthe ideal range of 15-30N). There was no statistically significantdifference between lipoaspirate control and lipoaspirate/silk fibroinparticle formulations. Large volumes (e.g., 20 mL or greater) of 15% v/vsilk fibroin particles in lipoaspirate can be extruded through 14Gneedles. Average extrusion force was not significantly increased byaddition of silk fibroin particles. The lipoaspirate bulked with silkfibroin particles extruded smoothly and consistently without clogs ormajor spikes in extrusion force which may otherwise cause pain ordiscomfort to patients during injection.

Additionally, since these silk fibroin particles can be easily extrudedat high concentrations, the high concentration of the silk fibroinparticles provides structural bulkiness, which can enhance shaperetention and malleability and allow for the formation of 3D structuresupon injection. This is also a unique feature of these silk fibroinparticles described herein over the conventional silk particleformulations that form a plug within the syringe and are difficult to beextruded from the needle. Such a unique feature of the silk fibroinparticles described herein is useful for sculpting and spreadingpost-injection or post-implantation when a specific geometry is desired.Further, when human lipoaspirate (“fat”) was extruded from the needle inthe absence of the silk fibroin particles, no 3-dimensional shape wascreated. This novel aspect of the silk particle formulation hasapplications for both tissue augmentation and fat grafting. Silk fibroinparticles described herein can be used as modifying materials fortraditional fat grafting applications, such as breast, buttocks andfacial enhancements, improving the predictability of volume retentionand long term tissue viability. Cells or tissues other than humanlipoaspirate could also be added, giving this formulation other uniqueutility.

Alternative applications beyond fat grafting may include fistulaocclusion or similar wounds caused by injury or surgery. For example, aninjectable silk particle formulation according to some embodimentsdescribed herein can seal the abnormal connection between two or moretissues, allowing epithelium to develop around the silk implant,reforming a natural epithelial barrier and preventing the exchange ofsubstances that may cause further infection or inflammation.Alternatively, injectable silk particle based bulking agents can be usedin urogenital applications. For example, urethral bulking—where bulkingmaterial is injected into the bladder neck and urethra—is used to treatincontinence due to sphincter deficiency. Injectable silk particles canbulk urethra walls, restoring the sealing mechanism, and be programmedfor long term volume retention for lasting effect. Similarly, injectablesilk particle formulations can be used to treat cervical insufficiency,a disease which is known to increase the risk of preterm labor. Aninjectable bulking agent comprising the silk fibroin particles describedherein into the walls of cervix can enhance the mechanics of thecervical canal to reduce the risk of early pregnancy. Current treatmentsfor cervical insufficiency include cervical cerclage, which is oftenassociated with hemorrhage, tearing, and difficult implantationprocedures. A minimally invasive injectable alternative may improvetissue mechanics without the drawbacks associated with sutures.

Example 8: Pore Characterization of a Silk Fibroin Material

To determine pore size and pore shape of a silk fibroin material, SEManalysis of silk fibroin material cross-sections was performed. Contrastwas manipulated using image analysis tool (e.g., Phenom Porometricsoftware/Nanoscience Instruments) such that silk fibroin are presentedas one color pixels (e.g., white pixels) and pores are presented as adifferent color pixel (e.g., black pixels). Then ellipses fit usingimage analysis tool to outline the pore shape was performed to determinepore size and/or pore shape of the pores.

FIG. 50A shows experimental data showing pore size distribution of porespresent in a freeze-dried silk fibroin material produced by one set ofembodiments of the methods described herein. FIG. 50B shows arepresentative SEM image of a cross-section of the silk fibroin sponges.As shown in FIG. 50A, the average circle equivalent diameter of poreswithin a silk fibroin sponge according to one set of the embodimentsdescribed herein is about 41.1 μm (ranging between about 31 μm and about51 μm). In some embodiments, at least about 35% of pores have a circleequivalent diameter of below 25 μm. In some embodiments, at least about50% of pores have a circle equivalent diameter of below 35 μm. In someembodiments, at least about 70% of pores have a circle equivalentdiameter of below 55 μm. In some embodiments, at least about 85% ofpores have a circle equivalent diameter of below 75 μm. In someembodiments, at least about 35% of pores have a circle equivalentdiameter of below 100 μm.

The pore shape can be characterized, for example, using an aspect ratioof pores and/or a circularity value for pores. The aspect ratio (AR) ofpores (AR=length (L)/width (W)), as shown in FIG. 12A, was determinedusing image analysis software. An AR value of 1 indicates a perfectcircular cross-section. In some embodiments, the silk fibroin spongeshave AR values near 1. FIGS. 12B-12C show the original image (left),contrast-enhanced image (middle), and ellipses fit image (right) ofdesirable rounded pore formation (FIG. 12B) and undesirable lamellarpore formation (FIG. 12C). FIG. 12D is a graph showing the aspect ratiodistribution of pores based on the cross-section of the silk fibroinsponge with pores of rounded morphology (desirable) or lamellarmorphology (undesirable). Silk fibroin sponges with desirable poreformation have pore aspect ratios where: approximately 20% or more ofthe pores have AR≤1.5; approximately 40% or more have AR≤2.0, andapproximately 10% or less have AR≥4.0. With respect to the aspect ratio,rounded pores can have values near 1.5, while lamellar pores may havevalues in excess of 5.0.

FIGS. 13A-13F show additional experimental data showing aspect ratios ofpores present in the silk fibroin sponge produced by the methoddescribed in the International Patent Publication No. WO 2016/145281.The aspect ratios were determined from SEM images of cross sections ofsilk fibroin sponges as described above. FIGS. 13A and 13D are SEMimages of cross-sections of the silk fibroin sponges. FIGS. 13B and 13Eshow the outline of the pores by ellipses fit. FIGS. 13C and 13F aredistribution graphs showing aspect ratios of the pores.

FIGS. 14A-14F show additional experimental data showing aspect ratios ofpores present in the silk fibroin material produced by the methoddescribed in the International Patent Publication No. WO 2013/071123.The aspect ratios were determined from SEM images of cross sections ofsilk fibroin materials as described above. FIGS. 14A and 14D are SEMimages of cross-sections of the silk fibroin sponges. FIGS. 14B and 14Eshow the outline of the pores by ellipses fit. FIGS. 14C and 14F aredistribution graphs showing aspect ratios of the pores.

FIG. 52 shows experimental data showing aspect ratio distribution ofpores present in a freeze-dried silk fibroin material produced by oneset of embodiments of the methods described herein. The aspect ratioswere determined from SEM images of cross sections of silk fibroinmaterials as described above. FIG. 50B shows a representative SEM imageof a cross-section of the silk fibroin sponges. As shown in FIG. 52 ,the average aspect ratio of pores within a silk fibroin sponge accordingto one set of the embodiments described herein is about 1.90±˜0.08. Insome embodiments, at least about 15% of pores have an aspect ratiobetween about 1 and about 1.33. In some embodiments, at least about 40%of pores have an aspect ratio between about 1.33 and about 2. In someembodiments, at least about 60% of pores have an aspect ratio betweenabout 1 and about 2. In some embodiments, at least about 95% of poreshave an aspect ratio between about 1 and about 4.

FIG. 53 shows experimental data showing circularity distribution ofpores present in a freeze-dried silk fibroin material produced by oneset of embodiments of the methods described herein. The circularity weredetermined from SEM images of cross sections of silk fibroin materialsas described above, wherein the circularity is determined as:(4πA_(pore)/P_(pore) ²), where A_(pore) is the average cross-sectionarea of the pores and P_(pore) is the average perimeter forming theboundary of the cross-section area of pores. The circularity value has ascale of 0 to 1, where a value of 1 refers to a perfectly round circle,while a value toward 0 trends toward either increasing perimeter (e.g.circumference) or decreasing area. FIG. 50B shows a representative SEMimage of a cross-section of the silk fibroin sponges. As shown in FIG.53 , the average circularity of pores within a silk fibroin spongeaccording to one set of the embodiments described herein is about0.672±˜0.026. In some embodiments, at least about 40% of pores have acircularity value between about 0.75 and about 1.00. In someembodiments, at least about 40% of pores have a circularity valuebetween about 0.50 and about 0.75. In some embodiments, at least about85% of pores have a circularity value between about 0.50 and about 1.00.In some embodiments, at least about 99% of pores have a circularityvalue between about 0.25 and about 1.00.

Example 9: Determination of In Vivo Immune Response and Degradation Rateof Compositions Comprising Silk Fibroin Particles According to SomeEmbodiments Described Herein

Silk fibroin particles produced from 10% w/v or 15% w/v silk fibroinsolution were implanted subcutaneously at an initial implant volume of500 μL into rats for 12 months. Silk fibroin particles allowinfiltration of surrounding macrophages into the porous structure.Minimal immune response (low immunogenicity), high cellularinfiltration, and volume persistence for the silk particles alone weredetected throughout 12 months as shown in FIG. 10 . FIG. 11 is a graphshowing in vivo degradation rate of silk fibroin particles alone uponimplantation into animals. The in vivo degradation rate was measured asa change in initial implant volume over time. Approximately 50% of theimplant volume remained 9 months after in vivo implantation.Extrapolation of the residence time by linear fit models was 18 months.

Example 10: Compressive Mechanical Analysis of Silk Fibroin Materials

The silk fibroin sponges were produced from the method described in theInternational Patent Publication No. WO 2016/145281. FIG. 15A showstress-strain profile of the silk fibroin sponges in hydrated state. Theelastic modulus (at 6-10% axial strain) of the silk fibroin sponges wasfound to be 72.4±5.2 kPa. FIG. 15B show compressive recovery for thesilk fibroin sponges in hydrated state. The silk fibroin sponges have ahigh recovery from at least 20% compressive strain (e.g., >90% recoveryto original shape/size after compression). Compressive recovery is, forexample, determined by comparing the height (e.g., largestcross-sectional dimension) of the sponge samples after compression vs.the height of the sponge sample before compression. Since the spongesare highly elastic, they nearly recover to their original size aftercompression.

FIG. 15C shows cyclic uniaxial compression of a population of silkfibroin particles (approximately 0.1 mL) measured under confinedcompression conditions. The silk fibroin particles were loaded into asyringe, and the bottom of the syringe was submerged in 1×PBS so thatthe particles were hydrated during compression testing. The syringeplunger (with the rubber removed to reduced friction) was replaced, andthe force transducer measured uniaxial force applied to the top of theplunger. Cyclic load/unload testing at 10% and 20% strains was performedat a rate of 1 mm/min. Compressed particle population recovered 91.2% ofits original volume when compressed to 20% uniaxial strain (in otherwords, exhibited greater than 90% recovery from 20% compression) and hada tangent modulus (compressive modulus) of 12.2 kPa when measured at 6%uniaxial strain, which is close to the native modulus of typical softtissues (which falls in the range of 1-10 kPa).

The compressive mechanics of the silk fibroin particles (FIG. 15C)appear to be softer when compared to the bulk sponges (FIGS. 15A-15B).The porous architecture of the bulk sponge may lend some mechanicalintegrity that might not be present once the bulk sponge was broken downinto discrete units—silk fibroin particles.

Example 11: Air Extrusion Force of Exemplary Compositions ComprisingSilk Fibroin Particles and Crosslinked Hyaluronic Acid (HA) as a Carrier

Crosslinked HA was used in the HA/silk particle formulations in thisExample. HA having a molecular weight of about 750 kDa to about 1000kDa, with a weight average molecular weight of about 823 kDa, wasdiluted and subject to a crosslinking reaction as follows: First, 1.5 gHyaluronic acid (Lifecore, 750-1000 kDa) was swelled in 0.25 M SodiumHydroxide (10.725 mL, NaOH) for two hours. Next, 771 μL of a 220 mg/mL1,4-butanediol diglycidyl ether (BDDE) solution (suspended in 0.25 MNaOH) was added to the hyaluronic acid and allowed to crosslink for twohours at 50° C. Afterwards, the HA was removed and 30 mL phosphatebuffered saline was added to quench the reaction. The crosslinked HAprepared at a concentration of 3% w/v was then mixed with silk particles(e.g., having a volume mean diameter of 425-500 microns) in a volumeratio of 60% (HA):40% (silk fibroin particles).

Extrusion forces of the compositions were measured as described inExample 3. FIGS. 16A-16B is a set of graphs showing extrusion force datausing a 1 mL syringe (21 gauge needle) for compositions comprising acrosslinked HA carrier, alone or in combination with silk fibroinparticles, according to one set of embodiments described herein. Thesilk fibroin particles were sieved to select particles of about 355 toabout 425 microns in diameter, and were about 40% v/v when mixed with60% v/v crosslinked HA gel. The crosslinked HA gel was prepared with acrosslinking agent (CA), e.g., BDDE, and hyaluronic acid disaccharides(HAD) in a CA:HAD mole ratio of about 22%. Extrusions were performed atrate of 1 mL/10 seconds or 5.5 mm/s.

FIGS. 17A-17B is a set of graphs showing extrusion force data using a 3mL syringe appended to a 18 gauge tulip cannula for compositionscomprising a crosslinked HA carrier in combination with silk fibroinparticles, according to some embodiments described herein. The silkfibroin particles were sieved to select particles of about 425 to about500 microns in diameter, and were about 40% v/v when mixed with 60% v/vcrosslinked HA gel (e.g., at about 2-3% w/v). The crosslinked HA wasprepared with a crosslinking agent (CA), e.g., BDDE, and hyaluronic aciddisaccharides (HAD) in a CA:HAD mole ratio of about 22% (FIG. 17A) or30% (FIG. 17B).

FIG. 18 shows the effect of needle gauge size on extrusion force of silkfibroin particle/crosslinked HA gel composition through 1 mL syringe.The composition comprises 40% v/v silk fibroin particles and 60% v/vcrosslinked HA. The silk fibroin particles were sieved to selectparticles between 355-425 microns in diameter. The crosslinked HA (e.g.,at about 2-3% w/v) was prepared with a crosslinking agent (CA), e.g.,BDDE, and hyaluronic acid disaccharides (HAD) in a CA:HAD mole ratio ofabout 22%. Extrusions of the silk fibroin particle/crosslinked HA gelcomposition occurred at a rate of 1 mL/15 seconds or 3.6 mm/s. The silkfibroin particle/crosslinked HA gel composition extrudes smoothly up to21G needle sizes. Extrusions are noisy using 22 gauge needles and theneedle is clogged while attempting to extrude the silk fibroinparticle/crosslinked HA gel through 23 gauge needles.

FIG. 19 shows the effect of varying volume ratios of silk fibroinparticle and crosslinked HA in formulation on extrusions through 21gauge needles. The silk fibroin particles were sieved to selectparticles between 355-425 microns in diameter. The crosslinked HA (e.g.,at about 2-3% w/v) was prepared with a crosslinking agent (CA), e.g.,BDDE, and hyaluronic acid disaccharides (HAD) in a CA:HAD mole ratio ofabout 22%. Extrusions of the silk fibroin particle/crosslinked HAcomposition occurred at a rate of 1 mL/15 seconds or 3.6 mm/s. As shownin FIG. 19 , extrusions of the compositions comprising 40% or 50% v/vsilk fibroin particles are smooth but at higher silk fibroin particleconcentrations, clogging sometimes occurs.

Example 12: Mechanical Analysis of Compositions Comprising Silk FibroinParticles and Crosslinked HA According to One Set of EmbodimentsDescribed Herein

FIGS. 20A-20D is a set of graphs showing rheometry data describing theshear properties for compositions comprising a crosslinked HA carrier incombination with silk fibroin particles according to one set ofembodiments described herein. The silk fibroin particles were about 355to about 425 microns in size, and 40% v/v silk fibroin particles weremixed with crosslinked HA gel. Dynamic rotational shear rheometry wasused to assess the mechanical features of crosslinked HA carrier aloneand silk fibroin particle/crosslinked HA compositions. The storagemodulus (G′), loss modulus (G″), complex modulus (G*) and dynamicviscosity were measured as a function of oscillatory strain andfrequency sweeps. Strain sweeps were performed from 0-200% at afrequency of 1Hz, and frequency sweeps were performed from 0.1-10 Hz ata shear strain of 1%. Testing was performed on a Discovery HR-3 (TAInstruments, New Castle, Del.) using a 40 mm diameter parallel plateattachment. For silk fibroin particle/crosslinked HA compositions, thenominal gap width used was 400 μm to accommodate the size of theparticles with a sample volume of 500 μL.

Oscillatory frequency sweeps from 0.1-10 Hz of FIG. 20A show that bothcrosslinked HA alone and silk fibroin particle/crosslinked HAcomposition behave elastically over the tested range. Both crosslinkedHA alone and silk fibroin particle/crosslinked HA composition respond toshear stress nearly independent of frequency, maintaining apredominantly elastic behavior with minimal change in tangent modulus.

Dynamic viscosity measurements of FIG. 20B reveal that both crosslinkedHA alone and silk fibroin particle/crosslinked HA compositiondemonstrate shear thinning behavior with increasing frequency. Thisproperty is highly relevant for ease-of-injection, where shear thinninghelps to reduce extrusion forces when injecting through small gaugeneedles.

Oscillatory strain ramps of FIG. 20C show how crosslinked HA alone ismore strain independent (therefore, resistant to strain inducedyielding) out to almost 100% strain, while silk fibroinparticle/crosslinked HA composition, though generally stiffer thancrosslinked HA alone, exhibit strain induced yielding as reflected byreduced stiffness observed at much lower strain (yielding begins atapproximately 1% strain). This behavior may account for the smootherextrusion profiles observed for silk fibroin particle/crosslinked HAcomposition during injection, as compared to extrusion profiles forcrosslinked HA alone. As shown in Example 20C, the stiffness (G′) of thecomposition according to one set of embodiments described herein (a) isdecreased by about 25%, as measured between about 0.1% strain and about1% strain; (b) is decreased by about 35-40%, as measured between about0.1% strain and about 10% strain; (c) is decreased by about 75-80% asmeasured between about 0.1% strain and about 100% strain; or (d) isdecreased by about 30-35% as measured between about 10% strain and about90% strain. By contrast, the stiffness (G′) of a correspondingcrosslinked carrier alone (e.g., crosslinked HA carrier alone) issubstantially constant until about 40% strain. The stiffness (G′) of thecrosslinked carrier alone (e.g., crosslinked HA carrier alone) isdecreased by only about 10-15%, as measured between about 0.1% strainand about 100% strain.

FIG. 20D compares the elasticity of the silk fibroinparticle/crosslinked HA compositions and crosslinked HA alone.Elasticity is a measure of how well a material returns to its originalshape after physical deformation and is calculated from the followingequation at frequencies of 1 and 10 Hz: Elasticity=100×[G′/(G′+G″)]. Asshown in FIG. 20D, both crosslinked HA alone and silk fibroinparticle/crosslinked HA composition offer favorable elasticity, withcrosslinked HA alone (darker bars) slightly greater than silk fibroinparticle/crosslinked HA composition (lighter bars).

Example 13: Determination of Final Crosslink Density in a Crosslinked HAGel

FIG. 21 is an illustration of an exemplary method to determine crosslinkdensity in a crosslinked HA gel. Protocol adapted from: Kenne et al.Carbohydrate Polymers (2013) 91: 410-418. The top left spectrumcorresponds to uncrosslinked HA. The dotted line box corresponds to thethree methyl protons on HA and possesses a peak at ˜2.0 ppm. The bottomleft spectrum corresponds to unreacted BDDE and possesses a unique peakat 1.7 ppm, which corresponds to the four methylene protons highlightedin the solid box. Crosslinked HA on the right of the figure possessesboth peaks. When BDDE reacts with HA, it is reactive with the —OH groupson the HA, so the peaks at 2.0 ppm in HA is always present, whether BDDEreacts with HA or not.

An exemplary protocol is described as follows: Digested 1 mL crosslinkedhyaluronic acid in 1 mL of a 1 mg/mL hyaluronidase solution suspended inPBS overnight at 37° C. Upon digestion, 100 μLs of the digested HA isadded to 600 μLs of deuterium oxide (D2O). Proton nuclear magneticresonance (1H NMR) experiments are performed to determine crosslinkdensity of a crosslinked HA. The crosslink density of a crosslinked HAis calculated as a ratio of the BDDE peak (1H NMR) to HA peak (1H NMR)multiplied by ¾ (i.e.,)

${{Crosslink}{density}} = {\frac{{integration}{}{BDDE}{peak}}{{integration}{HA}{peak}} \times \frac{3{HA}{protons}}{4{BDDE}{protons}}}$The crosslink density is reflective of the number of BDDE molecules inthe crosslinked HA divided by number of disaccharide repeats times 100%.

Using the protocol as described above, it was determined that the finalcrosslink density of a crosslinked HA (starting with 22% mol percentBDDE added for crosslinking reaction) is about 13%. The crosslinkingreaction is typically about 50-75% efficient.

Example 14: Mechanical and Biological Evaluation of Injectable SilkProtein Microparticle-Based Fillers for Treatment of GlotticInsufficiency

Ideal vocal fold injection augmentation materials should match nativetissue viscoelasticity, afford low needle resistance during delivery,and slowly resorb over time to allow cellular in-growth without animmunogenic response. A novel injectable silk proteinmicroparticle-based filler has been developed to meet these requirementsand restore the native bulk to vocal fold tissues while also displayingdurable in vivo longevity, promotion of cellular infiltration, andtissue regeneration.

The physical and mechanical properties of silk/hyaluronic acid (HA)materials were determined to characterize deformation resistance andrecovery compared to commercially available Prolaryn Plus®. Porcinevocal fold tissue was used to simulate the mechanical outcomes ofbulking procedures, while in vivo subcutaneous rodent implantationexamined immune response and volume retention.

Data demonstrated that highly porous, elastomeric silk microparticlespossess high recovery (at least 90% original volume) from compressivestrain. When combined with a hyaluronic acid carrier, rotational shearmodulus was in the range of soft tissues, 2-3 kPa, when measured from0.1-10 Hz. Silk/HA only causes minimal stiffening during in situinjections into porcine vocal fold tissue, increasing complex modulus by1.2× and 1.5× for 2-week and 7-week old animals, respectively, forinjections of 300 μL. Silk particles implanted subcutaneously in a ratmodel support ingrowth of adjacent tissue, retain up to 30% volume after12 months, and do not elicit a fibrotic response.

Accordingly, the physical properties of injectable silk/HA bulkingmaterials demonstrate that such formulations can be used for vocal foldaugmentation and treatment of glottic insufficiency.

Example 15: Mechanical Properties of Porcine Vocal Fold Tissue afterInjection of Silk/HA Compositions

This Example shows that silk/HA compositions described herein canadvantageously stiffen vocal folds to only a small degree afterinjection therein.

250-300 μL of a silk/HA composition were directly injected into thevocal fold bulk of porcine tissues using the catheter shown in FIG. 42 ,which had a needle gauge of 23XX. The silk/HA composition had an averagesilk particle size of less than 500 microns and a concentration ofparticles in HA of about 20-60% v/v. The composition had an averageextrusion force of <50 N through the needle of the catheter.

Vocal folds were excised and the mechanics of non-injected (“native”)and injected (“bulked”) tissues were assessed by dynamic rotationalshear rheometry employing the following procedure. The storage modulus(G′), loss modulus (G″), complex modulus (G*) and dynamic viscosity weremeasured as a function of oscillatory frequency sweeps from 0.1-10 Hz ata shear strain of 1%. Testing was performed on a Discovery HR-3rheometer (TA Instruments, New Castle, Del.) using a 40 mm diameterparallel plate attachment. For silk/HA compositions, the nominal gapwidth was 400 μm with a sample volume of 500 μL. Elasticity wascalculated at frequencies of 1 and 10 Hz using the following equation:

${Elasticity} = {100 \cdot \frac{G^{\prime}}{G^{\prime} + G^{\prime\prime}}}$Four hundred grit sand paper was used to reduce slippage. The gapdistance was modulated to achieve an axial force of 40-50 grams.

FIG. 36 shows rheology data indicating that ex vivo injection of silkparticles into 2 week old and 7 week old porcine (P) vocal fold tissuecaused less stiffening of native tissue compared to calciumhydroxylapatite (CaHA)-based injectable fillers. The fold-change ofbulked tissue was at most 1.5× for silk/HA and up to 4× for commerciallyavailable Prolaryn Plus®.

FIG. 37 shows elasticity data showing that the elasticity of all tissueswere similar, approaching 80%, and that bulking did not greatly impactdeformation recovery.

Example 16: Silk/HA Biocompatibility

This Example shows that silk/HA compositions described herein arebiocompatible.

Biocompatibility of a silk/HA composition was assessed using protocolsdescribed in ISO 10993. The silk/HA composition had an average silkparticle size of less than 500 microns, a concentration of particles inHA of about 20-60% v/v, and an average extrusion force of <50 N througha 23XX gauge needle of a catheter.

The genotoxicity was measured using the protocol described in ISOdocument 10993-5. This protocol is performed in vitro and includes thefollowing three tests: (1) Gene mutation (AMES) assay; (2) Mouselymphoma forward mutation; and (3) Rodent bone marrow micronucleus.

The acute systemic toxicity was measured using the protocol described inISO document 10993-11. These studies were performed in mice to evaluate:general effects on organs and organ systems from absorption,distribution, and metabolites after single exposure; and acute effects,such as gross pathology, body weight, adverse clinical signs. A singlemodel was chosen to evaluate all systemic toxicity. The observationswere performed for 72 hours and one week.

The intracutaneous reactivity was measured using the protocol describedin ISO document 10993-10. This is a test used to determine irritationusing rabbit models. The composition was injected and then theappearance was noted at 24 hours, 48 hours, 72 hours, and 14 days postinjection. At these time points, the edema was graded at each injectionsite.

Immunization/sensitization was measured using the protocol described inISO document 10993-10. This is a guinea pig maximization test fordetermining the allergic/sensitizing capacity of the composition. Thereis a first intradermal induction phase, which is followed by 7 day and14 day challenges with topical administration. Observations are made at24 hours and 48 hours, at which point the redness and swelling aregraded.

Table 2, below, summarizes the results from these tests.

TABLE 2 Biocompatibility of Silk/HA compositions. Test/Study ResultsGenotoxicity PASS-non-mutagenic PASS-no clastogenic effect AcuteSystemic Toxicity PASS-no significant reaction vs. controlIntracutaneous Reactivity PASS-no significant reaction vs. control AcuteSystemic Toxicity, PASS-non-reactive Intramuscular ImplantImmunology/Sensitization PASS-non-sensitizer

Example 17: Silk/HA Biocompatibility Animal Studies

This Example shows that silk/HA compositions described herein arebiocompatible.

Procedure: Animal procedures were carried out in full accordance withestablished standards set forth in the Guide for the Care and Use ofLaboratory Animals, 8th edition (NIH Publication No. 85-23). Animalswere sterilely housed and maintained pre- and post-operatively by theDepartment of Lab Animal Management (DLAM) and associated veterinariansat the Tufts University, Boston Campus. Two separate studies wereconducted to evaluate a) biocompatibility of the silk/HA formulation (aformulation having an average silk particle size of less than 500microns, a concentration of particles in HA of about 20-60% v/v, anaverage extrusion force of <50 N through a 23XX gauge needle) ascompared to a marketed calcium hydroxylapatite—carboxymethylcellulose(CaHA/CMC) filler (Prolaryn Plus®, Merz Neurosciences, Raleigh, N.C.),and b) the degradation profile of silk particles. A subcutaneous modelusing rats (female, 8 weeks; Taconic Biosciences, Germantown, N.Y.) wasused in both studies. Rats were anesthetized by isoflurane inhalation,3% for inoculation and 2% for maintenance. For evaluation ofbiocompatibility, N=3 animals per time point received subcutaneousinjections of 0.2 mL silk/HA or CaHA/CMC to each of the left and rightsides in the lumbar region. 3- and 6-month time points were selected toassess the progressive host in-growth and immunological response of theinjections. For evaluation of silk particle degradation, animalsreceived four injections of 0.2 mL of the silk/HA formulation on theleft and right side of the lumbar and scapular regions. A total of 15animals received injections, with N=3 for time points of 1, 3, 5, 9, and12 months. Animals were sacrificed by carbon dioxide asphyxiation andmajor organ removal as a secondary method. Samples were excisedincluding the adjacent dermal tissue and dimensions (length, width,height) of the remaining implant were recorded. Explants were placedinto tissue cassettes and immersed in 10% formalin for fixation. Tissueswere taken through standard dehydration processing, and bisected priorto paraffin embedding. Tissue sections were stained using hemotoxylinand eosin (H&E) and imaged using an inverted light microscope (AxiovertCFL 40; Carl Zeiss, Germany) and Q-Capture software (Qlmaging; Surrey,BC).

FIG. 38 is a micrograph showing a sample obtained at a 6 month timepoint for the silk/HA material. In this figure, the macrophage hasinfiltrated into the silk particle body. There is also giant cellformation, suggesting ongoing material breakdown. The silk has beenstained; it is also pointed to by the arrows.

FIG. 39 is a micrograph showing a sample obtained at a 6 month timepoint for the CaHA material. CaHA allowed cell migration around theparticles but not throughout the particle bulk.

FIGS. 40A and 40B are micrographs showing samples obtained at a 12 monthtime point for the silk/HA material. Particles have been heavilydegraded. Some volume persists. The silk has been stained; it is alsopointed to by the arrows.

FIGS. 41A and 41B are micrographs showing samples obtained at a 12 monthtime point for HA alone. HA degrades outside and there is scant cellularinfiltrate.

Example 18: Silk/HA Delivery System—Designed for One Surgeon, In-OfficeDelivery System

This Example shows that silk/HA compositions described herein can beefficiently delivered by catheters with advantageous designs asdescribed herein.

A silk/HA composition (a formulation with an average silk particle sizeof less than 500 microns, a concentration of particles in HA of about20-60% v/v, an average extrusion force of <50 N through a 23XX gaugeneedle) was delivered to canines by a catheter as described herein. Thecatheter was 50 cm long and had a 1.8 mm diameter. A 23XX gauge angledneedle was attached to the catheter and designed to interface with aflexible endoscope within a sheath. The sheath had an attached channelcomprising a laryngoscope to give an optimal viewing point for deliveryof silk injectable material into the vocal fold. The needle may besheathed until it is voluntarily engaged. Augmentation can be viewedfrom above during delivery of the material. FIG. 42 is a photograph ofthe catheter.

Procedure: The needle begins in the unsheathed (proximal position) inthe catheter. Next, the syringe is appended to the catheter handle andthe catheter is primed with silk/HA material (or the CaHA material asdescribed in Example 17 for the control experiment) to the opening ofthe needle. The catheter is next threaded through the cystoscope channeluntil the catheter tip protrudes out. The cystoscope/catheter device isnext inserted into the mouth of the canine. The needle is thenunsheathed from the catheter by changing the handle position.Afterwards, the vocal fold is punctured via the sheathed needle and 300μL of silk/HA material (or the CaHA material as described in Example 17for the control experiment) is injected into the right vocal fold of thecanine (see FIG. 43 , which shows silk/HA injection; note that the rightvocal fold appears as the left vocal fold). Afterwards the needle isremoved from the vocal fold and returned to the sheathed position viathe handle. Finally, the catheter is retracted from the cystoscope andthe canine is removed from the anesthetic.

FIG. 44 shows micrographs of the immediate post injection and 3 monthspost injection appearance of augmentation in a canine model for thesilk/HA composition. FIG. 45 shows micrographs of the immediate postinjection and 3 months post injection appearance of augmentation in acanine model for the CaHA material. The injections were performed intothe right vocal folds of each dog; the left vocal fold was used as anadditional control. Of note, there was no gross inflammation and bothmaterials were still present and bulky at 3 months.

Example 19: Silk/HA Canine Studies

This Example shows that silk/HA compositions described herein can bedelivered to canines, and have good properties for an extended period oftime after delivery.

A silk/HA composition (a formulation with an average silk particle sizeof less than 500 microns, a concentration of particles in HA of about20-60% v/v, an average extrusion force of <50 N through a 23XX gaugeneedle) was delivered to canine vocal folds using the catheter describedin Example 18. FIG. 46 shows the position at which it was placed(rectangles designate approximate section location; arrows designatehistologic face). FIGS. 47-49 are micrographs showing the excised vocalfold two months after injection. The left panel of each figure is acontrol (vocal fold lacking the silk/HA composition); the right panel ofeach figure is the vocal fold that has been injected with the silk/HAcomposition.

EQUIVALENTS

While several embodiments of the present invention have been describedand illustrated herein, those of ordinary skill in the art will readilyenvision a variety of other means and/or structures for performing thefunctions and/or obtaining the results and/or one or more of theadvantages described herein, and each of such variations and/ormodifications is deemed to be within the scope of the present invention.More generally, those skilled in the art will readily appreciate thatall parameters, dimensions, materials, and configurations describedherein are meant to be exemplary and that the actual parameters,dimensions, materials, and/or configurations will depend upon thespecific application or applications for which the teachings of thepresent invention is/are used. Those skilled in the art will recognize,or be able to ascertain using no more than routine experimentation, manyequivalents to the specific embodiments of the invention describedherein. It is, therefore, to be understood that the foregoingembodiments are presented by way of example only and that, within thescope of the appended claims and equivalents thereto, the invention maybe practiced otherwise than as specifically described and claimed. Thepresent invention is directed to each individual feature, system,article, material, kit, and/or method described herein. In addition, anycombination of two or more such features, systems, articles, materials,kits, and/or methods, if such features, systems, articles, materials,kits, and/or methods are not mutually inconsistent, is included withinthe scope of the present invention.

All definitions, as defined and used herein, should be understood tocontrol over dictionary definitions, definitions in documentsincorporated by reference, and/or ordinary meanings of the definedterms.

The indefinite articles “a” and “an,” as used herein in thespecification and in the claims, unless clearly indicated to thecontrary, should be understood to mean “at least one.”

The phrase “and/or,” as used herein in the specification and in theclaims, should be understood to mean “either or both” of the elements soconjoined, i.e., elements that are conjunctively present in some casesand disjunctively present in other cases. Multiple elements listed with“and/or” should be construed in the same fashion, i.e., “one or more” ofthe elements so conjoined. Other elements may optionally be presentother than the elements specifically identified by the “and/or” clause,whether related or unrelated to those elements specifically identified.Thus, as a non-limiting example, a reference to “A and/or B”, when usedin conjunction with open-ended language such as “comprising” can refer,in one embodiment, to A only (optionally including elements other thanB); in another embodiment, to B only (optionally including elementsother than A); in yet another embodiment, to both A and B (optionallyincluding other elements); etc.

As used herein in the specification and in the claims, “or” should beunderstood to have the same meaning as “and/or” as defined above. Forexample, when separating items in a list, “or” or “and/or” shall beinterpreted as being inclusive, i.e., the inclusion of at least one, butalso including more than one, of a number or list of elements, and,optionally, additional unlisted items. Only terms clearly indicated tothe contrary, such as “only one of” or “exactly one of,” or, when usedin the claims, “consisting of,” will refer to the inclusion of exactlyone element of a number or list of elements. In general, the term “or”as used herein shall only be interpreted as indicating exclusivealternatives (i.e. “one or the other but not both”) when preceded byterms of exclusivity, such as “either,” “one of,” “only one of,” or“exactly one of.” “Consisting essentially of,” when used in the claims,shall have its ordinary meaning as used in the field of patent law.

As used herein in the specification and in the claims, the phrase “atleast one,” in reference to a list of one or more elements, should beunderstood to mean at least one element selected from any one or more ofthe elements in the list of elements, but not necessarily including atleast one of each and every element specifically listed within the listof elements and not excluding any combinations of elements in the listof elements. This definition also allows that elements may optionally bepresent other than the elements specifically identified within the listof elements to which the phrase “at least one” refers, whether relatedor unrelated to those elements specifically identified. Thus, as anon-limiting example, “at least one of A and B” (or, equivalently, “atleast one of A or B,” or, equivalently “at least one of A and/or B”) canrefer, in one embodiment, to at least one, optionally including morethan one, A, with no B present (and optionally including elements otherthan B); in another embodiment, to at least one, optionally includingmore than one, B, with no A present (and optionally including elementsother than A); in yet another embodiment, to at least one, optionallyincluding more than one, A, and at least one, optionally including morethan one, B (and optionally including other elements); etc.

It should also be understood that, unless clearly indicated to thecontrary, in any methods claimed herein that include more than one stepor act, the order of the steps or acts of the method is not necessarilylimited to the order in which the steps or acts of the method arerecited.

In the claims, as well as in the specification above, all transitionalphrases such as “comprising,” “including,” “carrying,” “having,”“containing,” “involving,” “holding,” “composed of,” and the like are tobe understood to be open-ended, i.e., to mean including but not limitedto. Only the transitional phrases “consisting of” and “consistingessentially of” shall be closed or semi-closed transitional phrases,respectively, as set forth in the United States Patent Office Manual ofPatent Examining Procedures, Section 2111.03.

What is claimed is:
 1. A method for injecting a composition into a vocalfold, comprising: injecting a composition into the vocal fold, wherein:the composition comprises crosslinked hyaluronic acid, particlescomprising silk fibroin, and an anesthetic, a volume ratio of thecrosslinked hyaluronic acid to the particles is greater than or equal to50:50 and less than or equal to 75:25, the crosslinked hyaluronic acidhas a concentration in the composition of greater than or equal to 1%(w/v) and less than or equal to 10% (w/v), the crosslinked hyaluronicacid has a crosslink density of greater than or equal to 8 mol % andless than or equal to 20 mol %, the particles have an average particlesize of greater than or equal to 50 microns and less than or equal to500 microns, the particles comprise interconnected pores, the particleshave an average pore size of greater than or equal to 10 microns andless than or equal to 60 microns, and at least 50% of the interconnectedpores have a circle equivalent diameter of between 5 microns and 75microns.
 2. A method as in claim 1, wherein the injection occurs with anaverage extrusion force of less than or equal to 50 N.
 3. A method as inclaim 1, wherein the particles comprise glycerol, and wherein theparticles have a porosity of greater than or equal to 70% and less thanor equal to 95%.
 4. A method as in claim 3, wherein the particles havean average aspect ratio of greater than or equal to 1 and less than orequal to 3, wherein the composition further comprises non-crosslinkedhyaluronic acid, and wherein the non-crosslinked hyaluronic acid has amolecular weight of greater than or equal to 200 kDa and less than orequal to 1 MDa.
 5. A method as in claim 2, wherein the average extrusionforce is the average of the extrusion forces measured when extruding thecomposition through a catheter, and wherein the composition has acomplex shear modulus of greater than or equal to 1500 Pa and less thanor equal to 4000 Pa.
 6. A method as in claim 1, wherein no more than 10%of the interconnected pores have a diameter of 100 microns or greater.7. A method as in claim 1, wherein no more than 15% of theinterconnected pores have a circle equivalent diameter of 75 microns orgreater.